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S'mores Layer Cake

Prep Time 45 minutes
Cook Time 32 minutes
Total Time 1 hour 20 minutes
Servings 12

Ingredients

For the Chocolate Cake Layers

  • 2 cups all-purpose flour
  • 2 cups granulated sugar
  • 3/4 cup unsweetened cocoa powder
  • 2 tsp baking soda
  • 1 tsp baking powder
  • 1 tsp salt
  • 2 large eggs room temperature
  • 1 cup buttermilk room temperature
  • 1 cup hot coffee or hot water
  • 1/2 cup vegetable oil
  • 2 tsp vanilla extract

For the Graham Cracker Crumble

  • 1 1/2 cups graham cracker crumbs (about 10 full crackers)
  • 3 tbsp unsalted butter, melted
  • 2 tbsp granulated sugar

For the Marshmallow Buttercream

  • 1 cup unsalted butter, softened
  • 1 jar (7 oz / 198g) marshmallow fluff
  • 2 1/2 cups powdered sugar, sifted
  • 1 tsp vanilla extract
  • 3 tbsp heavy cream
  • Pinch of salt

Optional Topping

  • 2 cups mini marshmallows (for toasting)
  • Extra graham cracker crumbs
  • Chocolate ganache drizzle (1/2 cup chocolate chips + 1/4 cup heavy cream)

Instructions

Make the Chocolate Cake

  • Preheat your oven to 350°F (175°C). Grease and flour three 8-inch round cake pans. Line the bottoms with parchment paper.
  • In a large bowl, whisk together the flour, sugar, cocoa powder, baking soda, baking powder, and salt.
  • In a separate bowl or measuring cup, whisk together the eggs, buttermilk, oil, and vanilla extract.
  • Pour the wet ingredients into the dry ingredients and stir until just combined.
  • Carefully pour in the hot coffee and stir until the batter is smooth. It will be thin — that's completely normal and what makes this cake so moist.
  • Divide the batter evenly between your three prepared pans.
  • Bake for 30–35 minutes, or until a toothpick inserted in the center comes out clean.
  • Let the cakes cool in the pans for 15 minutes, then turn them out onto a wire rack to cool completely before assembling.

Make the Graham Cracker Crumble

  • In a small bowl, mix together the graham cracker crumbs, melted butter, and sugar until it resembles wet sand.
  • Spread onto a baking sheet and bake at 350°F for 8–10 minutes until lightly golden and fragrant. Let cool completely. It will crisp up as it cools.

Make the Marshmallow Buttercream

  • Beat the softened butter with a hand mixer or stand mixer on medium-high until light and fluffy, about 3 minutes.
  • Add the marshmallow fluff and beat until fully incorporated and smooth.
  • Reduce speed to low and add the sifted powdered sugar in two additions. Beat until combined.
  • Add the vanilla extract, pinch of salt, and 2 tablespoons of heavy cream. Beat on high for 2 more minutes until light and fluffy. Add the third tablespoon of cream if needed to reach a spreadable consistency.

Notes

Use room temperature ingredients. Cold eggs and buttermilk don't incorporate as smoothly into the batter. Take them out of the fridge about an hour before you start.
Don't skip the hot coffee. It enhances the chocolate flavor dramatically. If you're sensitive to caffeine, hot water works too — you'll still get a great result, just slightly less intense chocolate depth.
Cool your cakes completely. Frosting warm cake layers is a recipe for a melted, sliding mess. If you're short on time, wrap the cooled layers in plastic wrap and refrigerate them — cold cake is actually easier to frost.
Store leftovers in the fridge. This cake keeps well covered in the fridge for up to 4 days. Bring to room temperature for about 30 minutes before serving for the best texture.