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S'mores Cake

Chocolate cake layers with a graham cracker, marshmallow filling, then finished with a chocolate buttercream frosting, and topped with toasted marshmallows! This S'mores Cake is fun, easy, and delicious!
Prep Time30 mins
Cook Time35 mins
Course: Dessert
Cuisine: Cake
Keyword: S'mores Cake
Servings: 1 8" round cake



  • 1 15.25 ounce box Devil's Food Cake mix chocolate cake mix works too, and if the box is not exactly 15.25 ounces, it is okay
  • 3 large eggs
  • 1 cup vegetable oil
  • 1 3.4 ounce box instant vanilla pudding French vanilla pudding also works
  • 1 cup buttermilk *see below

Chocolate Buttercream

  • 1/2 cup unsalted butter softened
  • 1/2 cup vegetable shortening
  • 1/2 cup unsweetened cocoa powder
  • pinch salt
  • 1 teaspoon vanilla extract
  • 4 cups powdered sugar
  • 3-4 tablespoons heavy whipping cream


  • 4 tablespoons unsalted butter melted
  • 1 tablespoon brown sugar
  • 3/4 cup graham cracker crumbs
  • 2 cups mini marshmallows divided
  • Decoration
  • 18 regular sized marshmallows



  • Preheat oven to 350 degrees. Line 3, 8" round baking pans with parchment paper. Grease and flour sides of pans (I use Baking PAM to do this).
  • In a mixing bowl, stir mix together cake mix, eggs, vegetable oil, pudding, and buttermilk until all ingredients are just combined. Then, use electric mixer to beat on medium speed for about 2 minutes, or until batter is smooth.
  • Divide batter evenly among the 3 prepared pans. Bake for 28-30 minutes, or until toothpick inserted into center of cake comes out with just a few crumbs. Let cakes cool in pans for 10 minutes, then transfer to cooling rack. Let cool completely before decorating. NOTE: If you use a 9" pan, check the center of the cake after 25-26 minutes.

Chocolate Buttercream

  • Use electric mixer to beat together butter and shortening until lightened and fluffy, about 2 minutes. Add in cocoa powder, salt, and vanilla extract and beat until well combined.
  • Add powdered sugar 1/2 cup at a time. Beat until well combined and then beat in 1/2 tablespoon cream. Repeat adding powdered sugar and cream until desired consistency and taste are reached.

Graham Cracker Filling

  • Stir together graham cracker crumbs, melted butter, and brown sugar until well combined.

Assembly and Marshmallows

  • Level cakes with a serrated knife or cake leveler. On the top of TWO of the cake layers, use a piping bag to pipe frosting around the outside of the cake layers**. Fill the inside of each of the piped rings with 1/3 of the graham cracker mixture.
  • Turn oven to high broil. Line a cookie sheet with parchment paper. Place one of your 8" round baking pans on the parchment paper. Trace the bottom of the pan on the paper. Spray paper with cooking spray. In a single layer, spread 1 cup of mini marshmallows in the traced ring (leave about 1 inch between the outer marshmallows and the traced ring).
  • Place in oven and cook until marshmallows are golden brown. This takes about 2 to 3 minutes. Watch very closely as this happens quickly!
  • Place the browned marshmallows on top of the graham cracker crumbs on one of the cake layers. The sticky side of the marshmallows should be toward the graham crackers, and the browned side should be facing upward.
  • Repeat process with a clean piece of parchment paper and the remaining cup of mini marshmallows.
  • Stack the two filled cake layers on top of each other. Place the final cake layer, leveled side down, on top. Use frosting to frost outside and top of cake as desired (I use just a little so that the sides of the cake still peak through; see photos).
  • Again, turn oven to high broil. Line a cookie sheet with parchment paper and spray with cooking spray. Place large marshmallows on paper, an inch or two apart. Cook until marshmallows are golden brown. Again, this will take 2-3 minutes and you need to watch very closely.
  • Stack marshmallows on top of cake as desired.
  • Use remaining graham cracker crumbs to press into the sides of the bottom of the cake and sprinkle over the top of cake.


*If you do not have buttermilk, put 1 tablespoon of vinegar into a measuring cup. Fill cup to the 1 cup line with milk. Stir and let sit for 5 minutes.
**If you do not have a piping bag, cut off the tip of a corner of a Ziplock bag.