Preheat oven to 350°F.

Grease and flour (2) 8” round cake pans. Line bottom of pans with parchment paper. Set pans aside.

In a medium bowl, sift together the flour, baking soda and salt; set aside.

In a separate bowl, whisk together the cocoa powder and boiling water 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 sugar together on medium-high speed until light and fluffy (~4-5 minutes). (Tip: Don’t forget to scrape down sides and bottom bowl at least once during this step.)

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.

Divide batter evenly into prepared cake pans.

Bake at 350°F for 33-35 minutes, or until a toothpick inserted into the center of the cake comes out mostly clean.

Let cakes cool in the pans for about 20 minutes, then transfer to a cooling rack until completely cool. (Tip: Don’t forget to remove the parchment paper from the bottom of each layer.)

Using a countertop mixer, cream together the butter and marshmallow fluff until smooth (~2-3 minutes on medium high speed).

Add vanilla and milk; mix until well combined.

Add powdered sugar 1 cup at a time until desired consistency is reached.

Place one layer of cake on a large plate. Using an offset spatula, spread a thick layer of frosting on top of this layer. (Tip: Do not spread frosting all the way to the edge. Instead, leave about ½” border around the outer edge of each layer.)

Place second layer of cake on top.

Spread remaining frosting on sides and top of cake.

Garnish top of cake with mini-marshmallows and graham cracker crumbs. (Optional: Lightly toast mini-marshmallows using a kitchen torch.)