S'mores Chocolate Sheet Cake

Our favorite summertime treat in sheet cake form—no campfire required!

Southern Living Smores Sheet Cake sliced on a plate to serve

Molly Bolton

Active Time:
45 mins
Total Time:
2 hrs 30 mins

This S’mores Chocolate Sheet Cake has all the delicious flavors of a gooey, chocolatey s’mores, but without the campfire. Moist chocolate sheet cake topped with a layer of decadent chocolate ganache that’s covered in a smooth marshmallow buttercream frosting and toasty graham cracker crumbs. Easy to make and even easier to share!

Southern Living Smores Sheet Cake cut to serve on plates

Molly Bolton


Toasted Graham Cracker Topping

  • 3 graham cracker sheets, crushed into crumbs

  • 1 Tbsp. granulated sugar

  • 1 Tbsp. unsalted butter, melted 

  • 1/2 tsp. vanilla extract

  • 1/8 tsp. kosher salt

Chocolate Cake

  • Cooking spray

  • 2 cups all-purpose flour

  • 3/4 cup unsweetened cocoa powder

  • 2 cups granulated sugar

  • 1 tsp. baking powder 

  • 2 tsp. baking soda

  • 1/2 tsp. kosher salt

  • 2 tsp. espresso powder or instant espresso granules

  • 3/4 cup whole buttermilk, at room temperature

  • 1/2 cup sour cream, at room temperature

  • 1/2 cup vegetable oil

  • 2 large eggs, at room temperature

  • 2 tsp. vanilla extract

  • 3/4 cup hot coffee

Chocolate Ganache

  • 1 (4 oz.) bar semisweet chocolate, finely chopped

  • 1/2 cup heavy cream

Marshmallow Buttercream Frosting

  • 1 cup (8 oz.) unsalted butter, softened

  • 3 cups powdered sugar, sifted

  • 1 Tbsp. vanilla extract

  • 2 (7 oz.) containers marshmallow crème


  1. Make the Toasted Graham Cracker Topping:

    Preheat the oven to 300°F and line a rimmed baking sheet with parchment paper; set aside. Gather your ingredients.

    Southern Living Smores Cake ingredients

    Molly Bolton

    Add the graham cracker crumbs, sugar, melted butter, vanilla extract and kosher salt to a small bowl and stir to combine.

    Southern Living Smores Sheet Cake stirring together graham topping ingredients

    Molly Bolton

    Arrange the graham cracker crumbs in a single layer on the prepared baking sheet. Bake until lightly toasted and fragrant, about 7 to 8 minutes. Set aside to cool.

    Southern Living Smores Cake baking the graham cracker topping

    Molly Bolton

  2. Prepare the Chocolate Cake:

    Increase the oven temperature to 350°F. Generously grease a 9- x 13-in. baking pan with cooking spray; set aside. 

    In the bowl of a stand mixer fitted with the whisk attachment, add the flour, cocoa powder, sugar, baking powder, baking soda, kosher salt, and espresso powder. Whisk by hand until combined.

    Southern Living Smores Cake whisking together the dry ingredients for the cake

    Molly Bolton

    In a small bowl, whisk the buttermilk and sour cream together until smooth.

    Southern Living Smores Sheet Cake whisking together the sour cream mixture

    Molly Bolton

    Add the buttermilk mixture, vegetable oil, eggs, and vanilla extract to the bowl of dry ingredients and mix on medium speed until just combined, about 30 seconds.

    Southern Living Smores Cake chocolate batter mixed before adding coffee

    Molly Bolton

    Pour the hot coffee into the batter. Gradually increase the mixer to medium speed and mix until a smooth, thin batter forms.

    Southern Living Smores Cake adding the coffee to the cake batter

    Molly Bolton

  3. Bake the Cake:

    Pour the batter into the prepared pan.

    Southern Living Smores Sheet Cake batter in prepared pan before baking

    Molly Bolton

    Bake 30-35 minutes, until the top of the cake springs back when touched and a toothpick inserted in the center of the cake comes out clean. Set aside on a cooling rack while you prepare the ganache.

  4. Make the Chocolate Ganache:

    Place the chopped chocolate in a medium-sized, heatproof bowl; set aside. 

    In a small saucepan, warm the heavy cream on medium just until the edges of the cream begin to bubble (do not let it boil). Pour the warm heavy cream over the chopped chocolate and leave undisturbed for 2 minutes. Whisk the chocolate and cream until a smooth ganache forms.

    Southern Living Smores Sheet Cake ganache whisked together

    Molly Bolton

  5. Add Ganache:

    Spread the warm ganache evenly over the warm cake.

    Southern Living Smores Sheet Cake spreading the ganache on the cake

    Molly Bolton

    Allow the ganache to set and the cake to cool completely, either at room temperature or in the refrigerator, before topping with frosting.

  6. Prepare Marshmallow Buttercream Frosting:

    When the cake is cooled and the ganache is set, prepare the marshmallow buttercream frosting. Using an electric mixer, beat the softened butter on medium speed until creamy. Add the powdered sugar and vanilla extract, and beat on medium speed until combined and creamy. Add the marshmallow crème and mix on medium speed just until combined.

    Southern Living Smores Sheet Cake after mixing the frosting

    Molly Bolton

  7. Finish decorating Cake:

    Gently spread the frosting over the cake into an even layer.

    Southern Living Smores Sheet Cake spreading the frosting onto the cooled cake

    Molly Bolton

    Sprinkle with toasted graham cracker crumbs.

    Southern Living Smores Sheet Cake topped with graham cracker crumbs

    Molly Bolton

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