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S'mores cake

This dreamy s'mores cake features all the components of a classic s'more in the form of a toasted marshmallow meringue topping, rich chocolate cake and a buttery graham crunch.
Prep Time1 hour 30 minutes
Cook Time1 hour
Course: Dessert
Servings: 12 people
Author: Erika Kwee

Equipment

  • 9x13" pan metal preferred
  • 1 stand mixer with whisk and paddle attachments
  • baking sheet
  • parchment paper

Ingredients

Chocolate cake

  • 2 cups granulated sugar
  • 1 cup buttermilk, room temperature
  • 1 cup strong coffee, hot
  • 1/2 cup neutral oil avocado, refined coconut, vegetable, canola or algae oil all work
  • 3 large egg yolks, room temperature
  • 1 tsp vanilla extract
  • 3/4 cup Dutch-process cocoa powder
  • 2 tsp baking soda
  • 1 tsp baking powder
  • 1 tsp kosher salt
  • 1 3/4 cup all-purpose flour

Graham crunch

  • 6 tbsp granulated sugar
  • 4 tbsp unsalted butter
  • 3/4 cup graham cracker crumbs about 1/2 pack of graham crackers
  • 1/4 tsp kosher salt

Marshmallow meringue

  • 3 large egg whites*
  • 3/4 cup granulated sugar
  • 1/4 tsp cream of tartar
  • 3/4 tsp vanilla extract

Marshmallow buttercream

  • 1/2 cup unsalted butter, softened
  • 1.5 cups powdered sugar
  • 3/4 tsp vanilla extract
  • 1/4 tsp kosher salt
  • 1/2 cup marshmallow meringue
US Customary - Metric

Instructions

Make the chocolate cake

  • Preheat oven to 350 F. Grease and line a 9x13 pan with parchment.
  • In a large bowl, whisk together 2 cups granulated sugar, 1 cup buttermilk, room temperature, 1 cup strong coffee, hot, 1/2 cup neutral oil, 3 large egg yolks, room temperature (save the egg whites for later!) and 1 tsp vanilla extract. Sift in 3/4 cup Dutch-process cocoa powder and whisk to combine well.
  • Sprinkle over 2 tsp baking soda, 1 tsp baking powder and 1 tsp kosher salt and whisk to combine well. Finally, fold in 1 3/4 cup all-purpose flour using a spatula until just combined.
  • Pour batter into prepared pan and bake for 38-44 minutes, or until the middle springs back under your finger and an inserted tester comes out clean or with a few moist crumbs. Set aside to cool completely (I recommend chilling the cake in the fridge until cold for easier assembly).

Make the graham crunch

  • Once cake is done baking, reduce oven temperature to 325 F. In a small saucepan, combine 6 tbsp granulated sugar and 4 tbsp unsalted butter. Set over medium heat, whisking occasionally to help the mixture melt evenly.
  • Cook until the sugar has melted and mixture starts to bubble and look very foamy, around 3-4 minutes (mixture should reach around 215 F).
  • Remove from heat and immediately stir in 3/4 cup graham cracker crumbs and 1/4 tsp kosher salt. Pour crumbs on a parchment-lined baking sheet and bake for 7 minutes, or until crumbs are just lightly golden and fragrant. Set aside to cool completely.

Make the marshmallow meringue

  • In the bowl of a stand mixer or a heat proof bowl, whisk together 3 large egg whites* and 3/4 cup granulated sugar. Bring about two inches of water to a simmer in a small saucepan and set the bowl on top (don't let the bottom of the bowl touch the water).
  • Whisk the egg white mixture constantly until the sugar is dissolved and mixture is foamy and steaming (mixture should reach around 160 F), around 3-4 minutes. You can test if the mixture is ready by rubbing some of the mixture between your fingers--it should feel smooth with no granules of sugar.
  • Transfer hot mixture to a stand mixer fitted with a whisk attachment. Add 1/4 tsp cream of tartar and 3/4 tsp vanilla extract Whip on high speed until you reach stiff, glossy peaks, around 3-4 minutes.

Make the marshmallow buttercream

  • Transfer meringue to a separate bowl and replace the whisk with the paddle attachment (no need to clean the bowl). Beat 1/2 cup unsalted butter, softened until creamy and soft, then beat in 1.5 cups powdered sugar3/4 tsp vanilla extract and 1/4 tsp kosher salt until smooth.
  • Add 1/2 cup marshmallow meringue and beat until fully incorporated, about 30 seconds.

Assemble the cake

  • Torte the cooled cake (i.e. slice the cake horizontally) so you have two thin layers. Now slice the cake in half length-wise so you have four long rectangles.
  • Place a single layer of cake down on a cake board or serving plate. Top with 1/3 of the marshmallow buttercream followed by a small handful of the graham crunch, keeping a ~1" border around the edges (this helps the cake stick together--if you spread the crumbs too thickly and all the way to the edge, it's hard for the frosting to glue the cake together). Repeat with remaining layers of cake, buttercream and crunch, ending with a layer of cake. At this point, you may want to refrigerate the cake for at least 30 minutes (up to overnight) if the layers are getting warm and are starting to slip around.
  • To finish the cake, cover in half of the remaining meringue and use an offset spatula to do an initial crumb coat. Spread the remaining meringue over the cake, creating decorative swooshes all around the cake. You should have JUST enough meringue to cover the entire cake in light swooshes.
    Use a kitchen torch to lightly toast the sides of the cake until golden brown, being very careful to toast away from parchment paper or anything flammable. This cake is best served soon after toasting, though it will keep for a few hours in the fridge (uncovered).

Notes

With inspiration from Broma Bakery's s'mores cake.
See Ingredients section above for substitution suggestions for the buttermilk, coffee and cocoa powder.
*This recipe yields just enough meringue to incorporate some into the buttercream and frost the entire cake. If you'd like even more meringue to work with, use 4 large egg whites, 1 cup sugar, 1/2 tsp cream of tartar and 1 tsp vanilla extract.