Chocolate Marshmallow Radio Bars

These Chocolate Marshmallow Radio Bars feature a chocolate cake base topped with a scoop of marshmallow buttercream…oh yeah, and then they’re covered in a chocolate glaze!

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These Chocolate Marshmallow Radio Bars feature a chocolate cake base topped with a scoop of marshmallow buttercream...oh yeah, and then they're covered in a chocolate glaze!To the best of my knowledge, radio bars are a uniquely upstate New York thing.  More specifically, they’re a uniquely capital region of upstate New York thing.  More specifically, they’re a unique creation of one of the bakeries here in town.  Googling ‘radio bars’ only comes back with a sparse handful of results.  When was the last time you googled anything and came back with only a few hits?  I thought Google was broken.  Nope, it just turns out that radio bars aren’t as widespread as I thought.

These Chocolate Marshmallow Radio Bars feature a chocolate cake base topped with a scoop of marshmallow buttercream...oh yeah, and then they're covered in a chocolate glaze!So what is a radio bar?  Radio bars are pieces of chocolate cake topped with a spoonful (a ‘blop’ if you would) of frosting and then covered in a chocolate glaze.  I have no idea why they’re called radio bars.  I was thinking maybe they look like those old-timey radios?  But they really don’t.  So who knows how they got the name…and who cares!  All I know is they are delicious.  I can assure you with 100% certainty that these Chocolate Marshmallow Radio Bars will be a new favorite!

These Chocolate Marshmallow Radio Bars feature a chocolate cake base topped with a scoop of marshmallow buttercream...oh yeah, and then they're covered in a chocolate glaze!I was first introduced to radio bars when I was working at a local bakery right after we moved up here.  I’d taken a couple of professional baking classes at the local culinary school, and I decided it might be fun to open a bakery of my own.  I got a job working at a small ‘mom-and-pop’ bakery, and I’m glad I did…I quickly realized that I didn’t want to run my own bakery.  The quality of this particular bakery was downright bad.  Gordon Ramsay would’ve had a field day with this place!  But the one good thing that came out of those few months of being a semi-professional baker?  Radio bars.  (For the record, this bakery is not the original creator of the radio bar.  And this bakery is now thankfully out of business.)

These Chocolate Marshmallow Radio Bars feature a chocolate cake base topped with a scoop of marshmallow buttercream...oh yeah, and then they're covered in a chocolate glaze!Chocolate Marshmallow Radio Bars

“I hate you.”  Those were the words uttered by Laura after just one bite of these Chocolate Marshmallow Radio Bars.  We’re always careful with what we eat around here, and I had packed up these radio bars to send to her breakroom at work the next day.  But there was that one radio bar with a bite out of it, and I saved that one back for us.  Laura was right (as always often.)  I hated myself for wrapping up all of those radio bars.  Then again, I’m pretty sure her coworkers were quite pleased to walk into the break room and find a tray of these Chocolate Marshmallow Radio Bars!

These Chocolate Marshmallow Radio Bars feature a chocolate cake base topped with a scoop of marshmallow buttercream...oh yeah, and then they're covered in a chocolate glaze!Full disclosure: these bars are a bit of a process to make.  They’re not difficult by any means.  They just require a number of steps.  And after each step, it’s important to refrigerate (or ideally freeze) the bars so that the pourable frosting doesn’t turn the bars into an ooey, gooey mess.  Although, let’s be honest, I’d be ok with an ooey, gooey mess of radio bars.  Just hand me a fork, and I’ll clean up that problem!  But if you actually want to serve these bars to family or friends, then I do highly recommend taking the time to refrigerate/freeze the bars in between each step.  The result is worth it.  Trust me!

These Chocolate Marshmallow Radio Bars feature a chocolate cake base topped with a scoop of marshmallow buttercream...oh yeah, and then they're covered in a chocolate glaze!I hope you enjoy these Chocolate Marshmallow Radio Bars as much as we did!  They’re delicious, and I’m definitely filing this recipe away for when I need to take a fun dessert somewhere.  If you make this dessert, make sure to swing back by and leave a comment!  Or better yet, snap a photo and tag me on Instagram (@Spicedblog).  Happy baking, my friends!

Love chocolate?  C’mon…who doesn’t love chocolate?  Check out some of these other favorites!

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These Chocolate Marshmallow Radio Bars feature a chocolate cake base topped with a scoop of marshmallow buttercream...oh yeah, and then they're covered in a chocolate glaze!

Chocolate Marshmallow Radio Bars

These Chocolate Marshmallow Radio Bars feature a chocolate cake base topped with a scoop of marshmallow buttercream...oh yeah, and then they're covered in a chocolate glaze!
5 from 9 votes
Print Pin Rate
Prep Time: 15 minutes
Cook Time: 40 minutes
Total Time: 55 minutes
Servings: 12 squares
Calories: 931kcal


For the Chocolate Cake

For the Marshmallow Buttercream

For the Chocolate Frosting


For the Chocolate Cake

  • Preheat oven to 350°F.
  • Grease and flour sides of a 9”x13”baking pan; line bottom of pan with parchment paper. Set pan aside.
  • Using a medium mixing bowl, sift together the flour, baking soda and salt; set aside.
  • In a separate bowl, whisk together the cocoa powder and coffee until well combined. Stir in the milk and vanilla extract; set aside.
  • Using a countertop mixer fitted with the paddle attachment, cream the butter and both sugars together on medium-high speed until light and fluffy (~4-5 minutes).
  • Add the eggs one at a time, mixing until just incorporated after each addition.
  • Add half of the flour mixture to the bowl; mix on low speed until just combined.
  • Add half of the liquid mixture; mix on low speed until just combined.
  • Repeat with the remaining flour and liquid.
  • Pour batter into prepared pan. Bake at 350°F for 36-38 minutes, or until a toothpick inserted into the center of the cake comes out mostly clean.
  • Let cake cool in the pan for at least 30 minutes, then cover and transfer to a freezer for at least 60 minutes, or overnight.

For the Marshmallow Buttercream

  • Using a countertop mixer, cream together the butter and marshmallow fluff until smooth (~2-3 minutes on medium high speed).
  • Add vanilla and milk and powdered sugar 1 cup at a time, mixing well after each addition.
  • Place buttercream in refrigerator for 15-20 minutes.

For the Chocolate Frosting

  • Using a medium heatproof mixing bowl, whisk together powdered sugar, milk and vanilla extract; set bowl aside.
  • Using a medium saucepan, add sugar, cocoa powder, corn syrup, salt and ½ cup (1 stick) of butter. Place over medium-high heat and bring to a boil, stirring occasionally. Continue cooking until mixture reaches 240°F.
  • Remove saucepan from heat and slowly pour liquid into bowl with the powdered sugar, whisking constantly as you pour. Add remaining ½ cup (1 stick) of butter and stir until butter has completely melted.
  • Let mixture cool until just warm to the touch.

To Assemble

  • Remove the chocolate cake from the freezer and slice into 3”x3” squares.
  • Using two spoons (or a large piping tip), place a large scoop of buttercream onto the center of each square. Place squares back in freezer for 30 minutes.
  • Remove squares from freezer and pour warm (not hot) frosting evenly on top. (Tip: Place squares on a cooling rack set over a baking pan. That way, the pan catches any excess frosting as it’s poured.)
  • Place squares back in freezer for 15 minutes, or until chocolate frosting has hardened.
  • Serve chilled and store any leftovers in the refrigerator.

These Chocolate Marshmallow Radio Bars feature a chocolate cake base topped with a scoop of marshmallow buttercream...oh yeah, and then they're covered in a chocolate glaze!

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    1. Yeah, I hadn’t heard of radio bars until we moved up here, either, Kathy. Maybe they’re just a local specialty? Either way, they’re delicious! The big mound of frosting on top is always an eye-catcher! 🙂

  1. 5 stars
    I’ve never in my life heard of a radio bar, lol! So, clearly, I’ve been missing out! I like that little ‘bloop’ on top. Ok, I really like the whole thing. I’m thinking these would be SO good with a glass of vino tonight. Chocolate and wine are like bffs and, after all, it is Friday 😉 Pinned!

    1. Yeah, I have no idea where these radio bars got their name. And after a bit of searching, I suspect radio bars are just a local thing. But that bloop of frosting on top of chocolate cake can call itself whatever it wants…as long as it’s in my belly! And I second that thought about chocolate and a glass of vino. Cheers, Dawn!

    1. Ok, so the more I google, I’m beginning to suspect that radio bars are just a local thing. I have no idea where they came from or how they got their name…but whatever! They can call themselves whatever they want as long as they’re on my plate! 🙂 Thanks so much, Kelsie!

  2. 5 stars
    That top view of these babies looks amazing! Never heard of them, and I’m happy to now be in the know. Both my kids are big marshmallow fans, and of course would never turn down cake! After my first job in a restaurant kitchen I decided not to pursue being a pastry chef. Still love making pastries, but that job changed my path too. 🙂

    1. Why thank you so much, Valentina! I hear ya on the career path. After I left higher education, I thought for a brief moment that I wanted to be a professional baker or pastry chef. Then I realized those hours are terrible. Fortunately I stumbled into the blog world instead! I say let’s make a batch of radio bars and toast this crazy world we call blogging! 🙂

  3. Hi David! Like many I’ve never heard of radio bars, but I certainly wouldn’t turn one (or three) down! I agree that they take some time, but the end result is so worth it!! Now I want chocolate topped with chocolate! Have a great weekend and stay warm!

    1. I have no idea where this term ‘radio bar’ or even the concept comes from. I’m beginning to suspect it’s just a local thing. Either way, the idea of a big ‘bloop’ of frosting on top of a delicious chocolate cake is my idea of a good night! 🙂 Hope you had a great weekend, my friend!

  4. 5 stars
    DUDE!!! You had me at Marshmallow buttercream! This is my first time hearing of radio bars! What marvelous creations! I completely understand Laura’s sentiments – it would be so dangerous to have a tray of these in our home too – though I’m not sure i could actually wrap them up and share them! GAH!
    Hoping you guys have moved and unpacking is going well…

    1. So yeah, I think radio bars are a local thing. I have no idea where the name comes from…but then again, who cares about the name when you’ve got chocolate cake and marshmallow buttercream?? These bars are so delicious, Shashi!! As far as the move, it’s going. We’re in between closings right now, and we’re down to the last stuff (i.e. the strange stuff) to move over. Movers come this Friday to move all of the furniture. Send good luck…and soup! 🙂

  5. 5 stars
    Wow, David these are lovely! I’ve never heard of Radio Bars, but as good as they look and sound, you may assist them in going world-wide! I think you’rre Right about them looking like an old-time radio. And, I think I’d like to work right outside Laura’s Breakroom, if they get all your treats!

    1. Hah! I would be quite pleased if Radio Bars go world-wide, Laura. These bars are insanely delicious. Truthfully, they’re just another way to serve cake…but what’s not to love about a big ‘bloop’ of frosting on top of a cake square?? 🙂

  6. 5 stars
    How interesting! I’ve never heard of Radio Bars either, but their look reminds me some European toffee treats, not the radio. It’s a relatively simple dessert, but the frosting makes it look very lovely. You can also play a game with your quests: top one square with a scoop of ice cream, and the one who gets it instead of the frosting, would be a lucky person. Also, while “I hate you” is way too strong phrase, I’m certainly disappointed with you for not sending me a slice. Blacklisted. Haha, professional “black” humor 🙂

    1. I can see what you mean about the European toffee treats, Ben. Mmmm…toffee! 🙂 And you’re right that radio bars are a relatively simple dessert. Truthfully, they’re just another way to serve cake by putting a scoop of frosting on top of the cake rather than inside of it. Wait. Don’t blacklist me again, Ben. Nooooo….

  7. 5 stars
    This is the first time I’ve heard of a radio bar, but clearly I need an actual introduction. Yum!! I love all things chocolate and marshmallow (hello rocky road!). Definitely need to make these!

    1. “Radio Bars, meet Marissa.” “Marissa, meet Radio Bars.” There we go! 🙂 Seriously, though, radio bars are amazing. I think they’re just a super local thing, but they should be a national thing. I mean it’s cake with a big bloop of frosting on top…what’s not to love!? Thanks so much, my friend!

  8. These bars look so old-timey delicious! You know what? I almost bought a bakery once! Whoever did buy it did a great job, and is now selling bread in all the local groceries.

    1. Wait. You almost bought a bakery once? You’re like an onion, Jeff. There are just so many layers to peel away! I’d love to own a bakery, and I thought about it for about 1/2 a second…then I realized I didn’t want to wake up at 3am every day.

  9. Trust me, while I was reading this post of yours, Dilip was sitting next to me and he was looking on to my screen at that time and both of us looked at each other and said it looks so yummy!!!
    I am sure my daughter too would love this recipe of yours. Lovely sharing. 🙂

    1. Thank you so much, Puja! So the term ‘radio bar’ isn’t very common here in the States. I think it’s just a local term here in our town. But either way, this recipe is awesome! I mean it’s moist chocolate cake with a big bloop of frosting on top. 🙂 Thank you so much for the kind words, and tell Dilip thank you, too!

  10. 5 stars
    That chocolate glaze looks amazing David. Sorry to hear that bakery you worked in wasn’t that good. Still as you say at least these came out of them. And at least you honed cake making skills. Oh how I wish I was one of Laura’s co-workers. So that I too could enjoy all your delicious bakes!

    1. Why thank you very much, Neil! Truthfully, these radio bars are just cake masquerading under a different name. But they do look pretty cool, right?? I mean chocolate cake plus marshmallow frosting is pretty darned awesome! Heck, if I sprinkled some graham cracker crumbs on top, we could call these S’mores Radio Bars! 🙂

    1. Why thank you very much, Alexandra! Turns out radio bars aren’t really a “thing,” but they totally should be. These are SO good! 🙂

  11. its name is funny though! and i want to ask that when you just add those marshmallows, is the cake become sticky or not because i’ve tried a marshmallow cake once and i completely messed up with my cake.

    1. I totally know what you mean about marshmallows in cake, Mary! However, these radio bars only feature marshmallows in the frosting…not the actual cake. They weren’t sticky at all! Give these a shot and let me know what you think! 🙂

  12. if the cake is frozen when it comes out of the freezer how do u slice it when it’s frozen, shouldn’t u have to let it thaw for a while to do that? or doesn’t cake totally freeze rock hard?

    1. Great question, Vern! The frozen cake is still able to be sliced (it’s not rock hard). It’s firm enough to slice into nice, neat squares, but soft enough that you can still slice through it with a knife. I hope you enjoy this dessert…it’s a fun one for sure! 🙂

  13. I’m lucky enough to live near the bakery that created these bars of deliciousness. I can’t wait to try this recipe! If it’s even half as good as theirs it’s a winner. Thanks for sharing!

    1. Hey Patti! Greetings to a fellow resident of the Capital Region. 🙂 So I can’t make any claims about the original recipe to these bars. I just used them as an inspiration to invent this recipe. However, with that said, these radio bars are hands down delicious!! Let me know what you think! 🙂

  14. My Mom would buy us radio bars at a local bakery in the Pimlico section of Baltimore at least 70 years ago. The marshmallow on top of the cake which was all covered in chocolate was long and artfully done in a twisted shape, like some type of electrical energy wave, which I always assumed had some connection with radio.

    1. Interesting! I was thinking radio bars were a local thing here in the Albany, NY area, but your comment makes me realize they are a bit more widespread. And thanks for the insight into the name! The version here don’t look much like radios or energy waves, but I can say they are still quite delicious. 🙂

  15. I believe that I was present at the “naming” of the radio bar.
    Being a third generation bakery of a now 4th generation, 101 year old bakery, you can decide for yourself whether my account is of the original naming.
    In the St. Louis Metro area, there were several similar products of chocolate cake topped with marshmallow (actually boiled Icing) and coated with a chocolate glaze. My brother’s item was a slice of chocolate sheet cake, 3×1.5 inch size with two large “marshmallow piped shells” on top. He then froze the slice before dipping it in, not chocolate glaze, but milk chocolate. That made the product different than any other in the area. What to call it? Remember this was back in the mid 1970’s. Other bakeries called their products “dreamboats” or “chocolate delights”. His idea was to call them “Radio Bars”. They were in the shape of a “bar”, but then why “radio”? He half-jokingly said “they are meant to be a dessert following eating a “TV Dinner”. Remember those? He lived off of TV dinners when he was in college. The name “radio bar” stuck as it drummed up business when someone would ask “what are those?” “Those are ‘radio bars’.” “What’s a radio bar?” Going into the description the clerks seldom had someone refuse to buy some.
    We still make them the same way. They have been a favorite of customers even after they have moved on to other cities and states, always making sure that they took some back home after they came to visit. We have heard of these being made in various incarnations all over the U.S. but for my knowledge, it was here that they received the name “radio bars”.
    Jim Kruta

    1. Hey Jim! This is fascinating. I’ve always wondered where that term ‘radio bar’ came from. I just assumed it was something the local bakery here made up as I’ve never encountered the name anywhere else. However, it seems that radio bars actually originated over in St. Louis. I really appreciate your response – you’ve solved a mystery for sure! 🙂

      As far as the version at Kruta Bakery, they sound delightful. I can see why the clerks seldom have to go very far in the description. This homemade version is quite tasty, but I’d love to try the ones from Kruta. My wife sometimes travels to St. Louis for work (not these days…but maybe again someday), and I’ll tell her to look your bakery up if she has any free time!

      I just took a peek at your website, and there are so many things I want to try – that cinnamon apple ring is calling my name…and the almond bread claws…and the cinnamon bread…the list goes on and on. Thanks again for dropping by! Happy baking!

  16. If these are anything like the radio bars I have enjoyed from a bakery near Troy, NY, I can’t wait to try and make them. I LOVE LOVE LOVE these things, like addicted! My husband will treat me to one of these bars, or even better-the radio bar cake, and I just can’t get enough. I think I would make a ganache for the topping tho and dip. Thanks for sharing the recipe. I know what I’m doing this weekend 😉

    1. Hey Kelly! While I can’t promise these radio bars will be the same as the bakery version that you love, I can absolutely promise that these are delicious radio bars! They do take several steps to make, but I think the time spent is well worth it. 🙂 Happy baking!

  17. The Modern Bakery in Peekskill made Radio Waves–even more marshmallow frosting. It was a rounded rectangular cake–like a big chocolate twinkie cake–with a squiggle of marshmallow running the length of the cake, then the whole thing was covered in chocolate icing. There was a deli near my house in Croton that carried them. When I moved to Croton my husband and I would split a radio wave. By the time we left we were each eating an entire one on our own.

    1. Hey Kirsten! Thanks so much for taking the time to chime in here. 🙂 I’m not familiar with the Modern Bakery, but I’ll have to check them out next time we make our way down there. I really like the way the used the same flavors but mixed it up into a full cake version. Thanks for the idea!!

    2. I fondly remember going to Modern Bakery in Peekskill ny and buying Radio Waves. I loved then. They were the best.

      1. Thanks, Karen! Sadly I never made it to Modern Bakery, but it sounds like those Radio Waves were quite tasty. I do love this recipe – although it is a bit involved since there are several individual components. It’s worth it though!! 🙂

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