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S'mores Layer Cake

4.50 from 587 votes
prep 1 hour
cook 35 minutes
Additional Time 1 hour
total 2 hours 35 minutes
Serves 12 slices
This s’mores layer cake consists of graham cracker flavored cake layers, frosted with chocolate Swiss meringue buttercream and homemade heavenly marshmallow fluff.
Author: Bernice Baran
Servings 12 slices

Equipment

Ingredients

Cake

  • 65 grams (1/2 cup or 4-5 sheets) graham cracker crumbs
  • 240 grams (2 cups) all-purpose flour, spooned and leveled
  • 10 grams (1 Tbsp) baking powder
  • 1/2 tsp fine sea salt
  • 1/4 tsp cinnamon, *optional
  • 56 grams (1/4 cup) unsalted butter, room temperature
  • 120 mL (1/2 cup) canola oil
  • 100 grams (1/2 cup) granulated sugar
  • 200 grams (1 cup) light brown sugar, lightly packed
  • 1/2 Tbsp vanilla extract
  • 3 large eggs, room temperature
  • 240 mL (1 cup) buttermilk*, room temperature
  • 113 grams (1/2 cup/4 oz) dark chocolate chips
  • 120 mL (1/2 cup/4 oz) heavy cream

Meringue Frosting/Marshmallow Frosting

  • 6 (200g) large egg whites, room temperature
  • 300 grams (1 1/2) granulated sugar
  • 1 Tbsp vanilla bean paste

Chocolate Swiss Meringue Buttercream

  • 1/2 of Meringue frosting
  • 227 grams (1 cup/2 sticks) unsalted butter, room temperature
  • 1/2 of Chocolate Ganache
  • 1/2 cup (40g) Dutch-process cocoa powder, spooned and leveled
  • pinch of fine sea salt

Method

Graham Cracker Cake

  1. Preheat the oven to 350F/177C convection (or 325F/162C conventional) and grease and line three 6-inch (15.24 cm) cake pans with cooking spray and parchment paper. 
  2. Place 1 sleeve of graham crackers in a food processor and turn it on high until there are no more large chunks. In a medium bowl, whisk together the flour, graham cracker crumbs, baking powder, salt, and cinnamon. Set the dry ingredients aside. 
    65 grams (1/2 cup or 4-5 sheets) graham cracker crumbs, 240 grams (2 cups) all-purpose flour spooned and leveled, 10 grams (1 Tbsp) baking powder, 1/2 tsp fine sea salt, 1/4 tsp cinnamon *optional
  3. In an electric mixer fitted with the whisk attachment, beat the butter, oil, granulated sugar, light brown sugar and vanilla extract together, on medium speed, until they’re light and fluffy. This should take 2 to 3 minutes.
    56 grams (1/4 cup) unsalted butter room temperature, 120 mL (1/2 cup) canola oil, 100 grams (1/2 cup) granulated sugar, 200 grams (1 cup) light brown sugar lightly packed, 1/2 Tbsp vanilla extract
  4. Add the eggs, one at time, beating well after each addition. Make sure to scrape the bottom of the bowl as needed.
    3 large eggs room temperature
  5. In five increments, alternate adding the dry ingredients and buttermilk into the batter, beginning and ending with the dry ingredients. Beat the mixture on medium speed, just until the flour is fully incorporated, making sure to scrape the edge of the bowl as needed.
    240 mL (1 cup) buttermilk* room temperature
  6. Distribute the batter evenly among the prepared pans and bake for 30-35 minutes, until the cake springs back when it’s poked. Remove the cakes from the pans and allow them to cool completely before frosting.

Chocolate Ganache

  1. Place the dark chocolate in a medium bowl and in a small saucepan, heat the heavy cream until it's simmering. Pour the heavy cream over the chocolate and let it melt for 1-2 minutes. Stir until the chocolate is completely smooth. Set it aside to cool completely.
    113 grams (1/2 cup/4 oz) dark chocolate chips, 120 mL (1/2 cup/4 oz) heavy cream

Meringue Frosting/Marshmallow Frosting

  1. Begin by thoroughly cleaning the aluminum bowl and the whisk attachment of the stand mixer (they can’t have any fat residue when making meringue). Once they’re clean and dry, place the egg whites and the granulated sugar in the bowl.
    6 (200g) large egg whites room temperature, 300 grams (1 1/2) granulated sugar
  2. In a small saucepan, bring 1/2 cup (118mL) of water to a simmer. Keep the water simmering on low heat and place the bowl with the egg whites and sugar on top of the saucepan, creating a double boiler.
  3. Whisk the egg whites and sugar over low heat for 5 to 10 minutes, until the sugar granules are dissolved. You can feel it between your fingers if the sugar is fully dissolved but I HIGHLY recommend using a digital thermometer and bringing the mixture to 170°F (77°C) so the meringue is stable and doesn't weep.**
  4. When the sugar granules are fully dissolved in the egg whites and it reaches temperature, remove the bowl from the heat and place it on the stand mixer fitted with the whisk attachment. Beat the mixture on medium-high speed, until stiff peaks form.
  5. Add the vanilla and continue beating the mixture until it's no longer warm. This usually takes about 10-15 minutes. Remove half of the meringue into a separate bowl and set aside.
    1 Tbsp vanilla bean paste

Chocolate Swiss Meringue Buttercream

  1. Place half of the meringue back on the stand mixer and lower the speed to medium. Slowly add in the softened butter, 2 to 3 tablespoons at a time.
    1/2 of Meringue frosting, 227 grams (1 cup/2 sticks) unsalted butter room temperature
  2. Once the butter is all incorporated, continue beating on medium speed for a few minutes until it emulsifies into a buttercream (it may go through phases of looking soupy and/or curdled before it emulsifies but it should come together within 5-10 minutes). 
  3. Once the buttercream comes together, add in the cocoa powder, salt and only HALF of the melted chocolate. Mix well until it's completely smooth.
    1/2 cup (40g) Dutch-process cocoa powder spooned and leveled, pinch of fine sea salt

Assemble the Cake

  1. Place the first layer of cake on a cake board and spread a thin layer of chocolate buttercream on top. Then spread a layer of meringue frosting and a swirl of chocolate ganache (you can reheat the chocolate in the microwave for 5-10 seconds if necessary).
  2. Repeat with the second layer and then place the third layer of cake on top. If the buttercream is feeling too soft, refrigerate the cake for 15-30 minutes between stacking each layer.
  3. Smooth out any buttercream that squished out between the layers and refrigerate for at least 60 minutes. Place the rest of the chocolate buttercream on top of the cake and use an offset spatula to work it’s way down the sides.
  4. Add in dabs of meringue frosting and chocolate ganache, lightly spreading them in. Top with extra graham cracker crumbs, or even toasted marshmallows.

Notes

  • If the chocolate buttercream or the meringue frosting is too soft, refrigerate them for 20 minutes before frosting the cake. It's better for them to be slightly too firm instead of too soft.
  • *You can use a homemade buttermilk by mixing 1 cup of milk with 1 Tbsp of lemon juice or vinegar. **S’mores generally uses milk chocolate so I made this more nostalgic but if you’re like me and you like an elevated, less sweet s’mores treat, use dark chocolate instead of milk. I recommend adding an extra 1-2 Tbsp of heavy cream if using dark chocolate. 
     
  • **If you’re worried about the meringue weeping, make sure to get a thermometer and take the eggs to 175C – I promise it makes all the difference and don’t skip the cream of tartar. 
  • Alternatively if you need the meringue to last a long time, you may add in 1/4 tsp gelatin. Dissolve it in 1-2 tsp of cold water, let it set and then microwave it for 5 seconds before adding it into the fully whipped cream. Mix just until it’s well combined. Then when you refrigerate it, the meringue will set a bit and last a long time without weeping – can even be frozen like this. 

Nutrition

Serving: 1gCalories: 858kcalCarbohydrates: 105gProtein: 10gFat: 45gSaturated Fat: 21gPolyunsaturated Fat: 22gCholesterol: 132mgSodium: 361mgFiber: 2gSugar: 79g
Course: Cakes
Cuisine: American
Keyword: homemade marshmallow fluff, layer cake, s'mores cake, s'mores dessert, swiss meringue buttercream