S’mores Chocolate Cake
A dark Halloween-inspired s’mores cake made with ultra-moist chocolate cake layers using a blend of black cocoa and traditional cocoa powder. Each layer is filled simply with marshmallow fluff and toasted marshmallows, then surrounded and finished with a silky vanilla buttercream. A portion of the frosting is dyed deep black and piped into a dramatic spiderweb design for the final Halloween finish.
Equipment
- Three 8-inch round cake pans
- Parchment Paper
- Nonstick baking spray
- Large mixing bowl
- Kitchen scale, optional
- Stand mixer fitted with the whisk attachment
- Baking Sheet
- Parchment paper or silicone baking mat
- Cake turntable (optional)
- Serrated knife or cake leveler
- Piping Bags
- Medium round piping tip, optional
- Small round piping tip for spiderweb design
- Kitchen torch, optional
- Wire cooling racks
Ingredients
Chocolate Cake
- 2 cups all-purpose flour
- 2 cups granulated sugar
- 3/4 cup tablespoons natural unsweetened cocoa powder half black cocoa for deeper darker cake
- 2 teaspoons baking soda
- 1 teaspoon salt
- 2 large eggs room temperature
- 1 cup whole milk room temperature
- 1 cup vegetable oil
- 1½ teaspoons vanilla extract
- 1 cup boiling water
Marshmallow Filling
- 7 oz jar marshmallow fluff
- 1½ cups mini marshmallows plus more if desired for decorating
Optional S’mores Finish
- Crushed graham crackers for decorating the base or top
- Additional mini marshmallows for topping
Instructions
Prepare the Cake Pans
- Preheat the oven to 300°F.
- Grease three 8-inch round cake pans and line the bottoms with parchment paper.
- Lightly grease the parchment paper as well.
- The lower baking temperature comes from the original chocolate cake method and helps produce its particularly moist, tender texture.
Make the Chocolate Cake
- In a large mixing bowl, whisk together the flour, granulated sugar, natural cocoa powder, cocoa powder, baking soda, and salt.
- Add the eggs, milk, and vegetable oil.
- Whisk until everything is thoroughly combined and the batter is smooth.
- Stir the vanilla into the hot water.
- Slowly pour the hot vanilla water into the chocolate batter while whisking.
- Continue whisking until completely incorporated.
- The batter will be very thin. This is intentional. The high liquid content creates the especially moist texture of the finished cake.
Bake the Cakes
- Divide the batter evenly among the three prepared cake pans.
- Bake at 300°F for approximately 30–33 minutes, or until a toothpick inserted into the center comes out clean or with a few moist crumbs.
- Allow the cakes to cool in their pans for about 5–10 minutes.
- Carefully turn the layers onto wire racks and remove the parchment.
- Cool completely before filling or frosting.
- Once cool, use a serrated knife or cake leveler to remove any domes so all three layers are flat and even.
Prepare the Black Buttercream
- Reserve approximately 1 to 1½ cups of finished vanilla buttercream for the spiderweb decoration.
- Add black gel food coloring a little at a time.
- Mix until the frosting is very dark gray to black.
- Allowing the buttercream to rest for several minutes will help the black color deepen naturally, so avoid adding excessive food coloring immediately.
Assemble the Cake
- Place the first chocolate cake layer onto a cake board or serving plate.
- Pipe a thick ring of vanilla buttercream around the outer edge of the cake to create a sturdy dam.
- Spread approximately ½ to ¾ cup marshmallow creme inside the buttercream border.
- Sprinkle a generous layer of mini marshmallows directly over the marshmallow creme.
- Using a kitchen torch, carefully toast the marshmallow creme and mini marshmallows together directly on top of the cake layer until the marshmallows are golden and the creme develops lightly toasted, caramelized areas.
- Allow the toasted filling to cool briefly before placing the next cake layer on top.
- Place the second chocolate cake layer over the first.
- Pipe another thick vanilla buttercream dam around the outer edge.
- Spread another ½ to ¾ cup marshmallow creme inside the border.
- Add another generous layer of mini marshmallows.
- Torch the marshmallow creme and marshmallows together until toasted and lightly caramelized.
- Allow the filling to cool briefly, then place the final chocolate cake layer on top.
- Spread a thin layer of vanilla buttercream over the top and sides of the cake.
- Use an offset spatula or cake scraper to smooth the crumb coat.
Chill and Stabilize
- Refrigerate the assembled cake for about 20 to 30 minutes before frosting and decorating
- This helps firm the buttercream dams and stabilize the toasted marshmallow filling before frosting the outside.
Final Vanilla Buttercream Coat
- Apply a thicker final layer of vanilla buttercream over the entire cake.
- Smooth the sides and top or leave the frosting slightly textured, depending on the desired finish.
- Chill briefly before adding the black spiderweb so the design stays crisp.
Create the Spiderweb Design
- Use a spiderweb stencil and place around the chilled cake, pressing down.
- Take a frosting scraper and glide the black buttercream on top of the mold, pressing slightly to ensure the design is embedded in the stencil.
- Gently remove the stencil to reveal the spiderweb design. Repeat along all sides of the cake.
- Additional black buttercream can be used for a bottom border or other piped details.
Add the S’mores Finish
- For a more obvious s’mores presentation, finish the cake with a small amount of crushed graham cracker, toasted mini marshmallows, or chocolate pieces.
Notes
Why use both black and regular cocoa?
Black cocoa produces the dramatic dark appearance needed for the Halloween design, but using it as the only cocoa can give the cake a milder, more Oreo-like chocolate flavor. Splitting the original ¾ cup cocoa evenly into 6 tablespoons black cocoa + 6 tablespoons natural cocoa maintains stronger chocolate flavor while creating a much darker cake. Black buttercream develops over time.
Use gel rather than liquid food coloring. Getting the buttercream dark gray first and allowing it to rest often produces a deeper black without needing a huge amount of coloring. For cleaner layers:
Chill the cake after assembling and again after the crumb coat. The marshmallow fluff is naturally soft, so keeping the cake cool during decorating will make it much easier to work with. Storage:
Store the finished cake covered in the refrigerator for up to 3–4 days. For the best cake and buttercream texture, allow slices to sit at room temperature for approximately 20–30 minutes before serving. The original cake is likewise recommended cool rather than refrigerator-cold.
Black cocoa produces the dramatic dark appearance needed for the Halloween design, but using it as the only cocoa can give the cake a milder, more Oreo-like chocolate flavor. Splitting the original ¾ cup cocoa evenly into 6 tablespoons black cocoa + 6 tablespoons natural cocoa maintains stronger chocolate flavor while creating a much darker cake. Black buttercream develops over time.
Use gel rather than liquid food coloring. Getting the buttercream dark gray first and allowing it to rest often produces a deeper black without needing a huge amount of coloring. For cleaner layers:
Chill the cake after assembling and again after the crumb coat. The marshmallow fluff is naturally soft, so keeping the cake cool during decorating will make it much easier to work with. Storage:
Store the finished cake covered in the refrigerator for up to 3–4 days. For the best cake and buttercream texture, allow slices to sit at room temperature for approximately 20–30 minutes before serving. The original cake is likewise recommended cool rather than refrigerator-cold.
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