Ready to cast a delicious spell on your Halloween guests? To bake up a cake so dark, so rich, and so spectacularly spooky, it will be the talk of the party? This incredible, from-scratch “Black Magic” Chocolate Cake is the ultimate festive centerpiece! We’re talking a rich, dark-as-night, and impossibly moist chocolate cake, shrouded in a luscious, fudgy chocolate frosting, and enrobed in a ghoulishly gorgeous, sticky marshmallow spiderweb.
This isn’t just another cake recipe; it’s a guide to your new favorite show-stopping Halloween tradition. We’ll show you the simple but crucial secrets to the most intensely chocolatey cake and the brilliant, easy trick to creating that amazing, edible spiderweb decoration. This is a true Halloween showstopper that is as fun to decorate as it is to eat!
Table of Contents
Table of Contents
Recipe Overview: The Ultimate Spooky & Delicious Halloween Cake
What makes this “Black Magic” Cake so spectacularly fun is its incredible, dramatic appearance and its deep, rich chocolate flavor. This recipe is a masterpiece of festive baking. The cake itself is a soft and unbelievably moist, from-scratch dark chocolate cake, made extra rich by “blooming” the cocoa powder. The cake is then filled and frosted with a luscious, from-scratch, ganache-style chocolate frosting. The real magic, however, is the decoration. We’ll show you how to use simple, melted mini marshmallows to create an incredible, stretchy, and realistic-looking “spiderweb” or “mummy wrapping” all over the cake.
Metric | Time / Level |
Total Time | 2 hours 30 minutes (plus cooling) |
Active Prep Time | 45 minutes |
Difficulty Level | Easy |
Servings | 12-16 slices |
The Witch’s Pantry: The Essential Ingredients & Tools
This iconic party treat uses a handful of high-quality ingredients and one brilliant technique to create its signature spooky look.
- The “Black Magic” Chocolate Cake:
- Dutch-Process Cocoa Powder: This is the secret to the cake’s deep, dark color and its smooth, rich, and less acidic chocolate flavor.
- “Blooming” the Cocoa: This is a fantastic, professional baker’s secret! By stirring your cocoa powder into boiling water and letting it sit for a few minutes, you are “blooming” it. This simple step is the key that dissolves the cocoa solids and unlocks their deepest, most intense, and richest chocolate flavor.
- The Fudgy Frosting: A simple but incredibly decadent, ganache-style frosting made from heavy cream, Dutch-process cocoa, and good quality semisweet chocolate. A touch of espresso powder is the secret ingredient that will intensify and deepen the chocolate flavor without making the frosting taste like coffee.
- The Marshmallow Web:
- This is the brilliant and easy hack that makes this cake so spectacular! A simple bag of mini marshmallows, melted in the microwave, is the secret to the spooky decoration.
- Cooking Spray: This is your non-negotiable best friend for this step! Coating your hands in a neutral-flavored cooking spray is the key that will allow you to handle and stretch the sticky, melted marshmallow without it sticking to you.

Step-by-Step to the Best “Black Magic” Cake
This fun and festive project is a joy to prepare.
Part 1: Bake the “Black Magic” Chocolate Cakes
Step 1: First, preheat your oven to 350°F (175°C). Line the bottom of two 9-inch round cake pans with parchment paper, and then grease the parchment and the sides of the pans with oil.
Step 2 (The Secret to Intense Chocolate Flavor!): In a small bowl, stir together the 1 cup of Dutch-process cocoa powder and the 1 cup of boiling water. Let this mixture sit for 5 minutes to “bloom.”
Step 3: In a large bowl, whisk together the 2 cups of granulated sugar, the 1 3/4 cups of all-purpose flour, the 2 teaspoons of baking powder, and the 1 teaspoon of fine salt.
Step 4: In a separate, medium bowl, whisk together the bloomed cocoa mixture, the 2/3 cup of vegetable oil, the 1 cup of whole milk, the 2 large eggs, and the 1 tablespoon of pure vanilla extract.
Step 5: Pour the wet cocoa mixture into the dry sugar mixture and stir until the batter is smooth. The batter will be very thin—this is normal!
Step 6: Divide the batter evenly between your two prepared cake pans. Bake for 30 to 40 minutes, until the cakes bounce back when you press them in the middle and a toothpick inserted into the center comes out clean.
Let the cakes cool completely in their pans on a wire rack.
Part 2: Create the Fudgy Chocolate Frosting and Assemble
Step 1: To make the frosting, heat the 1 1/2 cups of heavy cream in a double boiler (or a heatproof bowl set over a saucepan of simmering water) over a low heat. Whisk in the 3/4 cup of sifted Dutch-process cocoa powder, the 8 ounces of chopped semisweet chocolate, the 1 teaspoon of espresso powder, the 1 teaspoon of pure vanilla extract, and the pinch of fine salt. Whisk until the mixture is completely smooth.Step 2: Whisk in the 2 tablespoons of unsalted butter until it has melted, and then whisk in the 1/3 cup of sifted confectioners’ sugar until it is incorporated. Let the frosting cool completely until it is thick and spreadable.Step 3: To assemble, place one of your cooled cake layers on a serving plate. Spread about 1 cup of the frosting over the top. Top it with the second cake layer and frost the top and the sides of the entire cake with the remaining frosting.
Part 3: The Art of the Marshmallow Web Decoration
Step 1: Place your 2 cups of mini marshmallows in a medium, microwave-safe bowl. Microwave for about 1 minute, until the marshmallows swell up and are soft.Step 2: Let the marshmallows sit for a few minutes until they are cool enough to touch.Step 3 (The Most Important Step!): Spray your hands generously with cooking spray.Step 4: Pick up a small, tablespoon-sized blob of the melted marshmallow. Using your fingertips, simply pull, stretch, and drape the sticky, web-like strands of the marshmallow over and around your frosted cake. Repeat this process, crisscrossing the strands in many directions, until you have a beautiful and spooky spiderweb covering your entire cake.Step 5: Garnish your web with a few candy spiders. If you are making a “mummy,” simply stretch the marshmallow strands in the same direction, leaving a small gap for the candy eyes.

‘Black Magic’ Halloween Cake (with Marshmallow Web!)
A rich and decadent, dark chocolate layer cake with a fun Halloween theme, called ‘Black Magic Cake’. The recipe features a moist chocolate cake made with bloomed Dutch-process cocoa for an intense flavor. Both the filling and frosting are a single, glossy chocolate ganache-style icing. For a spooky effect, the finished cake is decorated with a ‘spiderweb’ or ‘mummy’ design, cleverly created by stretching melted marshmallows over the frosted cake and adding candy spiders or eyes.
Ingredients
- For the Cake:
- 2/3 cup vegetable oil, plus more for greasing
- 1 cup Dutch-process cocoa powder
- 1 cup boiling water
- 2 cups granulated sugar
- 1 3/4 cups all-purpose flour
- 2 teaspoons baking powder
- 1 teaspoon fine salt
- 1 cup whole milk
- 2 large eggs
- 1 tablespoon pure vanilla extract
- For the Filling and Frosting:
- 1 1/2 cups heavy cream
- 3/4 cup Dutch-process cocoa powder, sifted
- 8 ounces semisweet chocolate, chopped
- 1 teaspoon espresso powder
- 1 teaspoon pure vanilla extract
- Pinch of fine salt
- 2 tablespoons unsalted butter
- 1/3 cup confectioners’ sugar, sifted
- For the Decoration:
- 2 cups mini marshmallows (about 4 ounces)
- Cooking spray
- Candy spiders or candy eyes
Instructions
- Make the Cake Layers: Preheat the oven to 350°F. Grease and line two 9-inch round cake pans with parchment.
- In a small bowl, stir together the cocoa powder and boiling water and let it sit for 5 minutes to ‘bloom’.
- In a large bowl, whisk the granulated sugar, flour, baking powder, and salt. In a separate medium bowl, whisk the bloomed cocoa, oil, milk, eggs, and vanilla.
- Pour the wet ingredients into the dry ingredients and stir until the batter is smooth (it will be thin). Divide the batter between the prepared pans.
- Bake for 30 to 40 minutes, until a toothpick inserted in the center comes out clean. Let the cakes cool completely in the pans.
- Make the Frosting: While the cakes cool, heat the cream in a double boiler over low heat. Whisk in the cocoa powder, chopped chocolate, espresso powder, vanilla, and salt until smooth. Whisk in the butter until melted, then whisk in the confectioners’ sugar. Let the frosting cool completely until it is a spreadable consistency.
- Assemble the Cake: Place one cake layer on a serving plate. Spread about 1 cup of the frosting over the top. Top with the second cake layer and frost the top and sides with the remaining frosting.
- Decorate: Microwave the marshmallows in a large bowl for about 1 minute until they swell. Let cool for a few minutes until you can touch them.
- Spray your hands with cooking spray. For a spiderweb, pick up blobs of the melted marshmallow and stretch them over and around the cake to create crisscrossing strings. For a mummy, stretch the strings in the same direction, leaving a gap for eyes.
- Garnish with candy spiders or candy eyes.
Notes
- ‘Blooming’ the cocoa powder in hot water is a key step that intensifies the chocolate flavor in the cake.
- It is crucial to let both the cake layers and the frosting cool completely before assembling the cake.
- The marshmallow web decoration is a fun, creative, and easy way to give the cake a spooky Halloween look.
- The article references a ‘Cook’s Note’ that is not provided in the text.
Storage and Make-Ahead Tips
This “Black Magic” Cake is a perfect make-ahead party treat!
- Make-Ahead: The unfrosted cake layers can be baked up to 2 days in advance. Let them cool completely, then wrap them very well in plastic wrap and store them at room temperature. The frosting can also be made a day in advance and stored, covered, in the refrigerator (you may need to let it soften at room temperature before using).
- Storage: Store the finished, decorated cake, loosely covered, at room temperature for up to 3 days.
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Frequently Asked Questions (FAQs)
Q1: What is the absolute, number one secret to a super moist and rich chocolate cake?
The secret is to use an oil-based batter and to “bloom” your cocoa powder. Oil is a liquid at room temperature, which guarantees a moister cake that stays soft for days. Blooming the cocoa in hot water is a brilliant trick that unlocks its deepest, most intense chocolate flavor.
Q2: What is Dutch-process cocoa powder, and is it important?
Dutch-process cocoa powder is a type of cocoa that has been treated with an alkali to neutralize its natural acidity. This is the secret that gives it a much darker, almost-black color, and a smoother, richer, and less bitter chocolate flavor. It is highly recommended for this “Black Magic” cake to achieve that stunning, dark color.
Q3: Can I make this Halloween cake ahead of time for a party?
Yes, absolutely! This is a perfect make-ahead cake. You can bake the layers and make the frosting a day or two in advance. It is best to assemble and decorate the cake on the day of your party for the freshest and most impressive result.
Q4: How do I keep the marshmallow web from being a completely sticky, unmanageable mess?
The non-negotiable secret is to generously coat your hands with cooking spray. This creates a non-stick barrier between your skin and the sticky marshmallow, which is the key that will allow you to easily pull and stretch the marshmallow into those beautiful, thin, web-like strands.
Q5: Can I make this recipe into cupcakes?
Yes! This cake batter makes fantastic, moist, and delicious cupcakes. Simply divide the batter among a lined, 24-cup muffin tin (filling each cup about two-thirds full). You will need to reduce the baking time to about 18 to 22 minutes.