Instructions

CAKE

1. Adjust an oven rack to the center position and heat oven to 350 degrees. Spray 3 8-inch round cake pans with nonstick baking spray and set aside. In a bowl, whisk together the flour, baking powder, cinnamon, nutmeg, baking soda and salt and set aside.
2. In the bowl of a stand mixer fitted with the paddle attachment attached, beat the butter on medium speed until smooth. Add the granulated and brown sugar and mix on medium high speed until light and fluffy, about 5 minutes.
3. On medium-low speed add the vanilla extract and mix until combined. Add the eggs and egg yolks one at a time, mixing well after each addition.
4. With the mixer on low speed, add the flour mixture in 3 batches, alternating with the buttermilk in 2 batches, starting and ending with the flour mixture. Mix on low speed for about 30 seconds, then finishing mixing by hand to blend any remaining bits of flour.
5. Divide the batter between prepared cake pans and bake for 23 to 25 minutes, or until a cake tester inserted in the center comes out with a few moist crumbs attached. Let cakes cool in their pans for 10 minutes, then invert on to cooling racks to cool completely.

CHOCOLATE FUDGE FILLING

1. In the bowl of a stand mixer with the paddle attachment attached, beat the butter on medium speed until smooth. Reduce the mixer speed to low, slowly add the powdered sugar, cocoa, salt and vanilla extract and mix until combined. Pour in the cream and mix to incorporate. Increase the mixer speed to medium and mix until the filling is light and fluffy. Scrape down the sides of the bowl and add the cooled melted chocolate and mix until smooth and combined.

MARSHMALLOW FROSTING

1. Attach the whisk attachment to the mixer stand. Add the egg whites, sugar, corn syrup, cream of tartar, and salt in the stainless steel bowl of a stand mixer and whisk together well by hand. Place the mixer bowl on top of a saucepan with about 2 inches of water, making sure the bottom of the mixer bowl does not touch the water when placed on top. Bring water to a simmer and place the mixer bowl on top. Whisk mixture frequently until a thermometer reaches 130 degrees, about 9 minutes.
2. Carefully transfer the mixer bowl to the mixer stand and beat on low speed for 2 minutes. Increase the speed to medium and beat for another 2 minutes. Increase the speed to high and beat for another 5 minutes until thick and glossy. Add in the vanilla extract and mix until combined. (Keep the saucepan of water to make the chocolate glaze.)

ASSEMBLE

1. Place once cake layer on a cake board or cake pedestal. Spread half of the chocolate filling on top in an even layer. Place a second layer of cake on top and spread remaining chocolate filling in an even layer on top. Place remaining cake layer on top. Frost the top and sides with marshmallow frosting. Refrigerate the cake for about 15 minutes. While the cake is chilling, prepare the chocolate glaze.

CHOCOLATE GLAZE

1. Bring the saucepan of water back to a simmer and place chopped chocolate, butter, corn syrup and salt in a heatproof bowl. Stir occasionally until the chocolate is melted and ingredients are combined. Set aside to cool slightly. (You want the chocolate just cool enough to not melt the frosting but warm enough for it to pour freely.)
2. Bring the chilled cake out of the refrigerator and pour just enough chocolate glaze to cover the top of the cake. Using a small offset cake spatula, gently push the glaze over the edge of the cake and chill the cake in the refrigerator for 10 minutes. Pour chocolate glaze on top for a second time, pushing chocolate glaze of the edge as desired. Chill the cake in the refrigerator for another 10 minutes.
3. Arrange marshmallows on top of the cake in a decorative fashion, securing marshmallows with toothpicks or wooden skewers as needed. Using a kitchen torch, lightly toast the marshmallows to your liking.
4. Crush a few graham crackers in a zip top bag with a rolling pin and sprinkle graham cracker crumbs on top of the cake just before serving.