Prepare three 8-inch cake pans with parchment paper circles in the bottom and grease the sides. Preheat oven to 300°F (148°C).

Add all dry ingredients to a large bowl and whisk together.

Add eggs, milk, and vegetable oil to the dry ingredients and mix well.

Add vanilla to boiling water and add to mixture. Mix well. The batter will be very thin.

Divide batter evenly between cake pans and bake for 30-33 minutes, or until a toothpick comes out with a few crumbs.

Remove cakes from oven and allow to cool for about 5 minutes, then remove to cooling racks to cool completely.

When the cakes are cooled and you’re ready to build the cake, preheat oven to 350°F. Line a cookie sheet with parchment paper or a silicone baking mat and set aside.

Combine the graham cracker crumbs, sugar, and melted butter and stir until well combined. Spread the crumbs evenly onto the prepared cookie sheet.

Bake for 8-10 minutes, then allow to cool. Set aside.

Toast the mini marshmallows under the broiler for about 1 minute, or until toasted. Remove from the oven and set aside to allow them to cool completely.

Add the butter to a large mixer bowl and beat until smooth.

Add the marshmallow fluff to the butter and beat until well combined.

Add about half of the powdered sugar to the butter mixture and mix until well combined and smooth.

Add the remaining powdered sugar and mix until well combined and smooth.

Add the cooled toasted marshmallows and mix until well combined. If the marshmallows are quite sticky, break them apart into smaller pieces before adding them to the frosting. Set aside.

Add the chocolate chips to a medium-sized bowl.

Heat the heavy whipping cream until it just begins to boil, then pour it over the chocolate chips.

Allow the chocolate and cream to sit for 3-5 minutes, then whisk together until smooth. Set aside.

Add the butter to a large mixer bowl and beat until smooth.

Add about half of the powdered sugar and mix until well combined and smooth.

Add the vanilla extract and cream and mix until well combined.

Add the remaining powdered sugar and mix until well combined and smooth.

Remove cake domes from the tops of the cake with a large serrated knife. Level the cakes if necessary.

Place the first layer of cake on a cake plate or cardboard cake circle. Pipe a dam of vanilla frosting around the outer edge of the cake to contain the filling.

Add about 6 tablespoons of chocolate ganache to the top of the cake and spread it into an even layer.

Add one cup of marshmallow frosting to the top of the ganache and spread into an even layer.

Add 1/2 cup of graham cracker crunchies to the top of the frosting and spread evenly.

Add the second layer of cake, another dam of vanilla frosting, then another layer of ganache, marshmallow frosting, and graham cracker crunchies.

Top the cake with the final layer of chocolate cake. Refrigerate the cake for about 30 minutes to firm up.

Use the remainder of the marshmallow frosting to frost the outside of the cake.

Press the remaining graham cracker crunchies into the bottom part of the cake.

Use the remainder of the chocolate ganache to add the chocolate drip to the cake. Gently heat the ganache if it has cooled too much.

Add some mini marshmallows to the top of the cake and use a kitchen torch to toast them.

Refrigerate cake until ready to serve. Cake is best when stored in an airtight container. Serve cool, but not cold, and finish leftovers within 3-4 days.