Graham Cracker Crumble

1. Preheat oven to 350ºF and prep a cookie sheet with parchment paper. Set aside.
2. Blend graham crackers in a food processor until they are a fine, sandlike consistency. Add in melted butter and sugar and blend until the crumbs start to clump together.
3. Pour the crumbs out onto the cookie sheet. Spread them out as much as possible. Bake for 10-15 minutes until toasted.
4. Let cool completely before transferring to an airtight container.

Chocolate Cake

1. Preheat oven to 350º F.
2. In a large bowl, whisk together the flour, baking soda, baking powder, cocoa powder, and salt and set aside.
3. In a stand mixer fitted with a paddle attachment, combine the butter and sugar on medium speed until light and fluffy.
4. Add eggs one at a time, followed by vanilla, scraping down the sides of the bowl with your spatula as needed.
5. With the mixer on low, add the buttermilk.
6. Beginning and ending with the flour mixture, alternate between adding the flour mixture and the coffee to the batter. Scrape down the sides of the bowl as needed.
7. Coat three 7-inch cake pans with cooking spray or butter and cocoa powder and line the bottom of each with parchment. Evenly divide the batter into the pans.
8. Bake for 35-38 minutes until a toothpick inserted in the center comes out clean.
9. Cool for 10-15 minutes on a cooling rack before gently running a knife along the edge of each pan, topping the cake with another cooling rack and turning each cake out. Let cakes cool completely before frosting.

Chocolate Frosting

1. Cream together the melted chocolate and butter on medium speed for 2-3 minutes until smooth.
2. With the mixer on low, slowly add in spoonfuls of the powdered sugar. Mix just until combined.
3. Scrape down the sides of the bowl, add in 1 tbsp of cream mix until light and fluffy. Add additional 1/2 tbsp if you'd like the frosting to be slightly thinner.
4. Chill frosting until needed.

Marshmallow Filling

1. Stir together the egg whites, sugar, and cream of tartar in a double boiler. Continue to stir constantly until mixture reaches 160º F on a candy thermometer.
2. Transfer to a mixing bowl, add in the vanilla, and mix with the whisk attachment on medium-high speed for 3-4 minutes followed by high speed for another 4-5 minutes until stiff peaks have formed.
3. Transfer marshmallow filling directly to a piping bag fitted with a large round piping tip like Ateco 807. You can also use a plastic bag and cut the corner off.

Cake Assembly

1. Once your cake layers have cooled, carefully cut the tops off with a serrated knife so that each layer is level.
2. Place one layer, top side down, on a cake board.
3. If your chocolate frosting has firmed up too much in the fridge, try remixing it back to piping consistency. If it's still too hard, let it sit out for about 5-10 minutes before transferring it to a piping bag with the tip cut off.
4. Pipe a border of chocolate frosting around the top of the first cake layer.
5. Pipe marshmallow filling inside that border and use an offset spatula to spread it evenly. Don't worry if it blends into the chocolate border.
6. Sprinkle a handful of graham cracker crumble on top of the marshmallow center. Top with a dollop of chocolate frosting to help secure it to the next cake layer.
7. Add the next cake layer on top and repeat the same process. Once the third cake layer is added, put the cake in the fridge to chill for 15-20 minutes.
8. Frost the top and sides of the cake with the remaining chocolate frosting. You'll have just enough and some of the marshmallow filling might ooze out a little, creating a beautiful marbled look in the frosting.
9. Once frosted completely, chill the cake again for another 15 minutes.
10. Place the cake over a cookie sheet and apply the remaining graham cracker crumble with your hand to the bottom half of the cake. You'll need to gently press it into the frosting and the cookie sheet will help catch the remaining crumbs.
11. Pipe 5 dollops of marshmallow filling on the top of the cake and gently toast with a kitchen torch, being careful not to melt the buttercream.
12. Enjoy!