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A s'mores layer cake sitting on a cake pedestal.

S'mores Layer Cake

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This s'mores cake is built Milk Bar style - layers of chocolate cake, toasted marshmallow frosting, fudge sauce, and graham crust crumbs!
Course Dessert
Cuisine American
Prep Time 1 hr 15 mins
Cook Time 35 mins
Freezer time 12 hrs
Total Time 13 hrs 50 mins
Servings 12 servings
Calories 762
Author Michelle


For the Fudge Sauce

  • 2 ounces dark chocolate finely chopped
  • ¼ cup Dutch-process cocoa powder
  • ¼ teaspoon kosher salt
  • ½ cup glucose (can substitute ¼ cup light corn syrup)
  • ¼ cup  granulated sugar
  • ½ cup heavy cream

For the Chocolate Cake

  • cups cake flour
  • ½ cup Dutch-process cocoa powder
  • teaspoons baking powder
  • teaspoons  kosher salt
  • ½ cup buttermilk
  • ¼ cup grapeseed oil
  • 1 teaspoon vanilla extract
  • ½ cup unsalted butter, at room temperature
  • cups granulated sugar
  • 3 eggs
  • 3 tablespoons Fudge Sauce

For the Graham Crust Crumbs

  • cups graham cracker crumbs
  • ¼ cup milk powder
  • 2 tablespoons granulated sugar
  • ¾ teaspoon kosher salt
  • ¼ cup unsalted butter, melted
  • ¼ cup heavy cream

For the Toasted Marshmallow Frosting

  • 16 large marshmallows
  • 1 cup unsalted butter, at room temperature
  • 1 cup powdered sugar
  • ½ teaspoon vanilla extract
  • 1⅔ cups marshmallow fluff

For the Cake Soak

  • ¼ cup milk
  • 1 teaspoon vanilla extract

Special Equipment


Make the Fudge Sauce

  • Combine the chocolate, cocoa powder, and salt in a medium bowl.
  • Combine the glucose, sugar, and heavy cream in a heavy-bottomed saucepan and stir intermittently while bringing to a boil over high heat. As soon as it boils, pour it into the bowl with the chocolate, cocoa powder and salt. Allow to sit for 1 full minute.
  • Begin to whisk the mixture very slowly. Continue, increasing the vigor of your whisking every 30 seconds, until the mixture is glossy and silky-smooth. This will take 2 to 4 minutes, depending on your speed and strength. You can use the sauce at this point or store it in an airtight container in the refrigerator for up to 2 weeks; do not freeze.

Make the Chocolate Cake

  • Preheat oven to 350 degrees F. Spray a quarter sheet pan with non-stick cooking spray and line with parchment paper, or with Silpat.
  • In a medium bowl, whisk together the flour, cocoa powder, baking powder, and salt.
  • In a measuring cup, combine the buttermilk, grapeseed oil, and vanilla extract.
  • Combine the butter and sugar in the bowl of a stand mixer fitted with the paddle attachment and cream together on medium-high for 2 to 3 minutes. Scrape down the sides of the bowl, add the eggs, and mix on medium-high for 2 to 3 minutes. Scrape down the sides of the bowl once more.
  • On low speed, gradually pour in the buttermilk mixture. Increase the mixer speed to medium-high and beat for 3 to 5 minutes, until the mixture nearly white, twice the size of your original fluffy butter-and-sugar mixture, and completely homogenous. There should be no streaks of fat or liquid (don’t rush this step!). Stop the mixer and scrape down the sides of the bowl.
  • Add the fudge sauce and mix on low speed until fully incorporated. Scrape down the sides of the bowl.
  • On low speed, gradually add the flour mixture and mix just until the batter comes together, about 45 to 60 seconds. Scrape down the sides of the bowl, and mix on low speed for another 45 seconds to ensure that any little lumps of cocoa powder and cake flour are incorporated.
  • Spread the cake batter in an even layer in the prepared pan. Bake the cake for 30 to 35 minutes; when you gently poke the edge of the cake with your finger, the cake should bounce back slightly, and the center should no longer be jiggly. Place the pan on a wire rack to cool completely. The cooled cake can be stored in the refrigerator, wrapped in plastic wrap, for up to 5 days.

Make the Graham Crust Crumbs

  • In a medium bowl, stir together the graham crumbs, milk powder, sugar and salt. In a small bowl, whisk together the butter and heavy cream, then pour over the dry ingredients. Using a fork, toss the mixture to ensure that it is evenly moistened and forming small clusters. Store in an airtight container for 1 week at room temperature, or up to 1 month in the refrigerator or freezer.

Make the Toasted Marshmallow Frosting

  • Place the marshmallows on a baking sheet lined with aluminum foil and sprayed with nonstick cooking spray. Place on the lowest rack of oven, and broil marshmallows until nice and brown on top, keeping an eye on them the entire time so they don’t burn. Remove pan from oven and gently turn the marshmallows over, and broil until the other side is golden brown.
  • Beat the butter and powdered sugar on low speed until blended together, about 1 minute. Add the vanilla extract and increase the speed to medium-high; beat for 3 minutes. Stop the mixer, add the Marshmallow Fluff and toasted marshmallows, and mix on the lowest speed for about 1 minute, scraping the sides of the bowl as necessary.

Assemble the Cake

  • Put a piece of parchment or Silpat on the counter. Invert the cake onto it and peel off the parchment or Silpat from the bottom of the cake. Use the cake ring to stamp out 2 circles from the cake. These are your top 2 cake layers. The remaining cake “scrap” will come together to make the bottom layer of the cake.
  • Layer 1, The Bottom: Clean the cake ring and place it in the center of a sheet pan lined with clean parchment or a Silpat. Use 1 strip of acetate to line the inside of the cake ring.
  • Put the cake scraps in the ring and use the back of your hand to tamp the scraps together into a flat even layer.
  • In a small bowl, whisk together the milk and vanilla extract for the cake soak. Using a pastry brush, brush half of the soak over the top of the cake.
  • Using the back of a spoon, spread one-fifth of the toasted marshmallow frosting in an even layer over the cake.
  • Dollop a few heaping tablespoons of the fudge sauce over the frosting and spread in an even layer.
  • Sprinkle one-third of the graham crust crumbs evenly over the top of the fudge sauce. Use the back of your hand to press them gently into the sauce.
  • Use the back of a spoon to spread a second fifth of the frosting as evenly as possible over the crumbs.
  • Layer 2, The Middle: With your index finger, gently tuck the second strip of acetate between the cake ring and the top ¼ inch of the first strip of acetate, so that you have a clear ring of acetate 5 to 6 inches tall. Set one of the cake rounds (the more imperfect of the two) on top of the frosting, brush with the remaining soak, and repeat the process for Layer 1 (a fifth of frosting, a layer of fudge sauce, a third of crumbs, and another fifth of frosting).
  • Layer 3, The Top: Nestle the remaining cake round into the frosting. Cover the top of the cake with the last fifth of the frosting, then another layer of fudge sauce. Garnish the frosting with the remaining graham crust crumbs.
  • Transfer the sheet pan to the freezer and freeze for a minimum of 12 hours to set the cake and filling. (The cake will keep in the freezer for up to 2 weeks.)
  • At least 3 hours before you are ready to serve the cake, pull the sheet pan out of the freezer and, using your fingers and thumbs, pop the cake out of the cake ring. Gently peel off the acetate and transfer the cake to a platter or cake stand. Let it defrost in the refrigerator for a minimum of 3 hours before slicing and serving. (You can store the cake, wrapped well in plastic wrap, in the refrigerator for up to 5 days.)


  • Canola oil can be substituted for the grapeseed oil.
  • The glucose is used to give body and smoothness to the fudge sauce. You can purchase glucose on Amazon, but can substitute corn syrup in the fudge sauce (see recipe above for amount), although the taste and texture will be altered, as corn syrup is sweeter and thinner.
  • After doing a couple of these cakes now, I've found that the actual cake is easier to handle after it's been chilled in the refrigerator.
  • You'll use some of the fudge sauce in the cake recipe, and more for layering the cake, but you may have some leftover. Save it for your ice cream! :)
Nutritional values are based on one serving


Calories: 762kcal | Carbohydrates: 92g | Protein: 7g | Fat: 43g | Saturated Fat: 23g | Cholesterol: 136mg | Sodium: 576mg | Potassium: 297mg | Fiber: 3g | Sugar: 64g | Vitamin A: 1155IU | Vitamin C: 0.2mg | Calcium: 110mg | Iron: 2.2mg