This Red Velvet Marshmallow Spiderweb Cake is a classic red velvet cake frosted with deep black chocolate buttercream and wrapped in a spooky marshmallow spiderweb.
It’s been a few years since I last made a spiderweb cake, so I revisited the idea with a different take: a red velvet layer cake covered in rich black chocolate buttercream and finished with delicate strands of marshmallow spun into an edible cobweb. The result is dramatic, festive, and surprisingly easy to pull off.
The marshmallow web technique—melting marshmallows and pulling them into long, stringy strands—was inspired by a classic cake-decorating post. Warm, melted marshmallow can be stretched into fine threads that you wrap around the chilled cake to form a spooky, airy web. It’s quick to do, a little messy, and completely edible.
I finished the cake with a candy spider made from chocolate plastic (a simple mixture of melted candy coating and corn syrup that firms up and can be kneaded and sculpted like a pliable candy dough). Chocolate plastic is easy to make, tastes like chocolate, and becomes firm enough to hold shape after resting. You can also use fondant, marzipan, or a store-bought chocolate spider if you prefer.
For the decoration I used black chocolate buttercream, colored with a concentrated gel food coloring to achieve a true black shade. Starting with a chocolate base helps reach a rich black more easily than trying to color white buttercream, and the chocolate pairs nicely with red velvet. I also reserved a small amount of red frosting to add bright streaks along the top and sides for contrast and a bit of spooky flair.
The marshmallow cobweb looks best when applied to a very cold cake or a fondant-covered cake. If your frosting doesn’t crust, chill the frosted cake until the buttercream is very firm before wrapping the marshmallow strands to avoid pulling the frosting. Apply the marshmallow web shortly before serving since the strands can become sticky over time.
Cream cheese frosting is traditional for red velvet, but I chose chocolate buttercream to give the cake more structure for the marshmallow web and a complementary flavor. The buttercream recipe here makes a light, silky frosting that holds its shape well and accepts strong gel colors without thinning.
The candy spider is made by mixing melted candy coating with a bit of light corn syrup until it forms a soft paste. After resting overnight the mixture firms up and can be kneaded and shaped. Shape a larger oval for the body and a smaller ball for the head, press them together, add sugar pearls for eyes, and roll thin legs with tapered ends. Attach parts with a touch of corn syrup if needed and chill to set.
To pull the marshmallow strands: microwave large marshmallows in a microwave-safe bowl for roughly one minute, stir, and heat in short bursts until melted and smooth. Let the marshmallow cool slightly until warm but not scalding, then pinch a small amount between your fingers and pull it out into very thin strands. Wrap the strands across and around the cake, changing direction as you go, until you’ve built up a layered cobweb. If the marshmallow cools and becomes difficult to stretch, warm it briefly and continue.
One practical tip: assemble the marshmallow web right before serving because the strands will soften and become sticky over time. The cake itself—layers and frosting—can be prepared in advance and refrigerated; decorate with marshmallow and place the spider when ready to serve.
👻 More Halloween Recipe Inspiration 👻
- Matcha Chocolate Tarts
- Devil’s Food Cake with Pumpkin Butterscotch Frosting
- Skull Cake for Dia de los Muertos
- Spiderweb Cupcakes and Chocolate Spiders
- Sugar Cookie Pinwheels
- Donut Hole Eyeballs
- Red Velvet Hot Chocolate
Zombie Brain Brownie Bites
Breaking Bad Blue Rock Candy
Red Velvet Marshmallow Spiderweb Cake
Ingredients
For the Candy Spider:
- 6 oz red candy coating melts
- 2 TBSP light corn syrup
- Black pearl sprinkles for eyes
For the Red Velvet Cake:
- 11.25 oz all-purpose flour (about 2 1/2 cups)
- 10.5 oz granulated sugar (about 1 1/2 cups)
- 1 tsp baking soda
- 1 tsp salt
- 2 tbsp unsweetened cocoa powder
- 8 fl oz vegetable oil (1 cup)
- 12 fl oz buttermilk (1 1/2 cups)
- 2 large eggs
- 2 tbsp red gel food coloring
- 1 tsp white vinegar
- 2 tsp vanilla extract
For the Buttercream:
- 6 oz unsweetened chocolate, finely chopped
- 4 fl oz pasteurized liquid egg whites (1/2 cup)
- 16 oz powdered sugar (4 cups)
- 1/4 tsp salt
- 16 oz unsalted butter (4 sticks), at room temperature
- 1 TBSP vanilla extract
- Red gel food coloring (for accents)
- Black gel food coloring (for the black chocolate frosting)
To Decorate:
- 6 oz large marshmallows
Instructions
To Make the Candy Spider:
- Melt the red candy coating in the microwave until smooth. Stir in the corn syrup until the mixture forms a thick paste. Scrape onto plastic wrap, wrap tightly, and let rest overnight.
- The next day, dust your work surface with powdered sugar and knead the firm candy plastic until pliable. Shape an oval body and a smaller head, press them together, and add sugar pearls for eyes. Form eight tapered legs and attach them with a touch of corn syrup if needed. Chill to set.
To Make the Red Velvet Cake:
- Preheat the oven to 350°F. Line four 8-inch cake pans with parchment and spray with nonstick spray.
- Sift together flour, sugar, baking soda, salt, and cocoa powder.
- In a mixer bowl, combine oil, buttermilk, eggs, red gel, vinegar, and vanilla. Mix until combined.
- Add dry ingredients and mix on low until combined, then on medium until smooth. Divide batter among pans (about 12 oz batter per pan if using a scale).
- Bake 20 minutes or until cakes spring back to the touch. Cool completely. Cakes can be baked ahead, wrapped, and refrigerated or frozen.
To Make the Buttercream:
- Melt the chocolate and let it cool to room temperature.
- Combine egg whites, powdered sugar, and salt in the mixer and beat on low until moistened, then on medium for 5 minutes.
- With the mixer on medium-low, add softened butter a tablespoon at a time. Add vanilla, scrape the bowl, then beat on medium for 10 minutes for a light, fluffy frosting.
- Reserve about 1/2 cup of frosting and tint it red for accents. Stir the melted chocolate into the remaining frosting, then tint with black gel coloring until you reach the desired black shade.
- Frosting can be stored refrigerated (up to two weeks) or frozen (up to two months). If chilled, bring it to room temperature and re-whip before using.
To Decorate:
- Stack and fill the cake layers, apply a thin crumb coat of frosting, and chill until firm (about 45 minutes).
- Apply the final layer of black chocolate buttercream. Add streaks of red frosting and gently blend so the red still pops. Chill the cake until the frosting is very firm (1–2 hours).
- Microwave marshmallows until melted and smooth. Let cool until warm but not hot. Pinch a small amount and pull it into thin strands between your fingers, wrapping them around the chilled cake to form a web. Continue layering strands at different angles until you’re happy with the coverage. Reheat briefly if the marshmallow becomes too stiff to pull.
- Top the web with the candy spider, allow it to come to room temperature if chilled, and serve within a few hours for best texture—the marshmallow strands will become sticky over time.
Recipe Notes
The marshmallow spiderweb technique was inspired by a cake-decorating tutorial that stretches melted marshmallow into fine strands. The chocolate plastic spider is a mixture of melted candy coating and corn syrup that firms up after resting overnight. Store-bought fondant can be used instead if preferred.
Measuring Tips
These recipes were developed using weight measurements—using a kitchen scale gives the most consistent baking results. Volume measurements are included for convenience, but when precision matters, weigh your ingredients.
Nutrition
Carbohydrates: 77 g |
Protein: 6 g |
Fat: 44 g |
Saturated Fat: 30 g |
Cholesterol: 83 mg |
Sodium: 321 mg |
Potassium: 176 mg |
Fiber: 2 g |
Sugar: 56 g
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