Using a food processor or mini-chopper, pulse the graham crackers until finely ground.

In a medium bowl, combine the graham cracker crumbs, brown sugar, and melted butter. Stir until fully combined.

Lightly butter or grease a 9” springform pan. Line the bottom of the pan with a circle of parchment paper. Press the crust mixture evenly into the bottom of the pan. (Tip: A flat-bottomed glass helps pack the crust mixture down evenly.)

Bake crust at 350°F for 5 minutes. Remove from oven and let cool.

Reduce oven temperature to 325°F.

Using a countertop mixer, beat the cream cheese and marshmallow fluff on medium speed until completely smooth (about 3 minutes).

Add the sugar and mix well. (Tip: Don’t forget to scrape the bottom and sides of the mixing bowl to fully incorporate the sugar.)

Whisk the eggs and egg yolks together and add to the bowl in 3 additions, mixing fully after each addition.

Add the sour cream, vanilla extract and cinnamon; mix until fully combined. (Tip: Use a spatula to scrape the sides and bottom of the bowl to ensure the filling is fully mixed.)

Sprinkle chocolate chips and marshmallows evenly over the crust and then pour cheesecake filling on top.

Wrap the bottom of the pan with a piece of aluminum foil and place in a large baking pan. Fill pan with about 1/2”-3/4” of water. Bake at 325° until center of cake is just barely set (~80-85 minutes). (Note: If brown spots appear on top of the cheesecake, it’s ok! That’s a result of the sugars in the marshmallow fluff. You’ll be covering the cheesecake in chocolate soon enough anyways!)

Remove cheesecake from oven and let cool at room temperature for 30 minutes.

Cover cheesecake lightly with foil or plastic wrap; refrigerate for at least 2 hours or overnight. (Tip: I actually like to wrap my cheesecake in plastic wrap and then freeze it overnight. It makes it easier to remove from the pan and slice.)

Using a small saucepan, add chocolate chips and whipping cream. Place over medium-low heat and cook, stirring occasionally, until chocolate chips are fully melted.

Spread melted chocolate over top of cheesecake.

Spread marshmallows on top of cheesecake. Place cheesecake under broiler (in oven) for 1-2 minutes, or until marshmallows are lightly toasted. (Note: Watch this stage very closely to prevent marshmallows from burning under the broiler. Another option is to use a kitchen torch to toast the marshmallows.)

Refrigerate cheesecake for at least 2 hours before serving.

Crumble additional graham crackers on top of cheesecake immediately before serving.