Chocolate Mousse Cake

Hello friends! This Chocolate Mousse Cake is the ultimate indulgence for any chocolate lover. Imagine layers of rich chocolate cake, a silky-smooth chocolate mousse, and a glossy chocolate ganache finish, all coming together to create a decadent dessert that’s perfect for celebrations or any special occasion. With its stunning presentation and luxurious flavors, this cake will impress everyone who takes a bite!

Best Chocolate Mousse Cake Recipe

In this post, I’ll guide you through each step of making this show-stopping cake, from preparing the moist chocolate cake layers to assembling with creamy mousse and decorating with ganache. This recipe yields one 9-inch cake.

Full ingredients, prep time, and total time amounts, as well as step-by-step instructions, can be found at the bottom of this post!

Preparing the Chocolate Cake Batter

Start by preheating your oven to 350°F (175°C). Grease and line two 9-inch cake pans with parchment paper.

In a large mixing bowl, whisk together the flour, sugar, cocoa powder, baking powder, baking soda, salt, and espresso powder (if using).

In another bowl, combine the eggs, vegetable oil, buttermilk, sour cream, and vanilla extract, mixing until smooth. Pour the wet ingredients into the dry ingredients and stir until combined. Add the brewed coffee and whisk until the batter is smooth and liquid.

Divide the batter evenly between the prepared pans. Bake for 30–35 minutes, or until a toothpick inserted in the center comes out clean. Cool the cakes in the pans for 15 minutes, then remove and allow to cool completely.

Pro Tip: Wrap and freeze the cake layers if not assembling the same day for easier handling.

Making the Chocolate Mousse

Before starting, prepare your workspace by measuring and separating all ingredients. Keep the heavy cream chilled until needed.

Chocolate Mixture: Melt the milk and dark chocolate in a large bowl, stirring until smooth. Let cool slightly, then whisk in the egg yolks one at a time, followed by the salt and vanilla.

Gelatin Mixture: Bloom the gelatin by sprinkling it over cold water. Heat ½ cup of cream until steaming, then dissolve the gelatin in the hot cream. Gradually mix the gelatin mixture into the chocolate mixture.

Whipped Cream: Whip the remaining cream until stiff peaks form. Set aside.

Whipped Egg Whites: Beat the egg whites with cream of tartar until foamy, then gradually add sugar while beating to stiff peaks.

Fold: Gently fold the whipped cream into the chocolate mixture in two additions. Next, fold the egg whites into the chocolate mixture in two additions.

The mousse will be runny but will set as it chills.

Assembling the Cake

You’ll need a 9-inch pastry ring or springform pan with acetate for assembly.

If using a springform pan, you probably won’t be able to fit all the mousse in the pan, so you can either halve the mousse recipe in that case, or divide the leftover mousse that didn’t fit between ramekins.

Place one cake layer in the base of the ring or pan, ensuring the acetate is secured around the edges.
Pour the mousse over the cake layer. Gently place the second cake layer on top. Refrigerate overnight or for at least 8 hours to set.

Making the Ganache

Combine the chopped dark and milk chocolate in a bowl. Heat the cream and corn syrup until steaming, then pour over the chocolate. Let sit for a minute, then whisk until smooth. Allow the ganache to thicken at room temperature for about an hour.

Decorating the Cake

Carefully remove the pastry ring and acetate from the cake. Spread the ganache over the top and sides. Garnish with fresh berries and chocolate shavings for a beautiful finish.

Storage

Store the cake in the refrigerator for up to 3 days. For longer storage, freeze individual slices in airtight containers for up to 1 month.

Tips & Tricks

• Before starting, read through the entire recipe and ensure you have all ingredients and tools ready. Preparing everything ahead of time (mise en place) will make the process much smoother.
• Use a kitchen scale to measure ingredients accurately, especially for baking, as precise measurements are crucial for success.
• Use room-temperature eggs, buttermilk, and sour cream for better incorporation into the batter.
• Adding hot coffee not only enhances the chocolate flavor but also ensures a moist and rich cake. If you don’t have coffee, hot water with a pinch of espresso powder works well.
• The batter will be thin, so pouring it into a measuring cup or bowl with a spout can help you divide it evenly between the pans.
• Use high-quality chocolate for the mousse; it will make a big difference in flavor. A combination of milk and dark chocolate creates a perfect balance of sweetness and richness.
• Be gentle when folding the whipped cream and egg whites into the chocolate mixture to maintain their volume. Overmixing can deflate the mousse, resulting in a denser texture.
• If your mousse seems runny, don’t worry—it will firm up once refrigerated.
• Acetate sheets are essential for creating smooth edges and preventing the mousse from leaking. You can find acetate online or at baking supply stores, or online.
• If you don’t have a pastry ring, a springform pan with acetate works well, but consider halving the mousse recipe to avoid overflow.
• For a silky ganache, chop the chocolate finely so it melts easily when combined with the hot cream.
• Let the ganache cool to room temperature before spreading it over the cake.
• If the ganache splits (looks grainy), add a tablespoon of warm milk or cream and whisk until smooth.
• This cake is best served chilled. Remove it from the fridge about 10–15 minutes before serving to allow the ganache to soften slightly.
• Store leftovers in an airtight container in the fridge for up to 3 days. If you have extra mousse, serve it in ramekins as a delightful standalone dessert.

Variations

• Chocolate Raspberry Delight: Add a layer of raspberry preserves between the cake and mousse.
• Coffee Lover’s Twist: Add 1–2 tsp of instant espresso powder to the mousse for a mocha flavor.
• Nutty Crunch: Fold chopped hazelnuts or almonds into the mousse for added texture.

Why You’ll Love This Chocolate Mousse Cake

This cake is rich, creamy, and downright luxurious, making it perfect for birthdays, anniversaries, or any time you want to treat yourself to a little decadence. The combination of moist chocolate cake layers, airy mousse, and velvety ganache creates a harmonious blend of textures and flavors that will impress any chocolate lover.

It’s an elegant dessert that not only tastes incredible but also looks stunning, with its glossy ganache finish and customizable decorations like berries or chocolate shavings. Despite its show-stopping appearance, this cake is surprisingly achievable with the step-by-step instructions provided, making it ideal for both special occasions and indulging in a weekend baking project.

Whether you’re sharing it with loved ones or savoring it for yourself, this chocolate mousse cake will make every bite feel like a celebration.

If you love this recipe, check out these other desserts:

• Chocolate Bomb
• Chocolate Cheesecake
• Chocolate Birthday Cake
• Brigadeiros (Chocolate Fudge)

Happy baking, friends! Let me know how your cake turns out and share your photos with me on Instagram.

Chocolate Mousse Cake

Camila Hurst

This Chocolate Mousse Cake is the ultimate indulgence for any chocolate lover with layers of rich chocolate cake and fluffy mousse!

5 from 3 votes

Print Recipe Pin Recipe

Prep Time 1 hour hr 25 minutes mins

Cook Time 35 minutes mins

Cool Time 9 hours hrs 15 minutes mins

Total Time 11 hours hrs 15 minutes mins

Course Dessert

Cuisine American

Servings 16 servings

Calories 650 kcal

Ingredients

  

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Chocolate Cake Batter

• 2 cups all-purpose flour 255 grams
• 1¾ cup granulated sugar 350 grams
• ⅓ cup cocoa powder 34 grams
• 1 tsp baking powder
• 2 tsp baking soda
• ½ tsp salt
• ½ tsp espresso powder optional
• 2 large eggs
• ½ cup vegetable oil 120 ml
• ⅔ cup buttermilk 158 ml
• ⅓ cup sour cream 75 grams
• 2 tsp vanilla extract
• 1 cup brewed coffee 200 ml

Chocolate Mousse

• 1¼ cup chopped milk chocolate 212 grams
• 1¼ cup chopped dark chocolate 212 grams
• 4 large yolks
• ½ tsp salt
• ½ tbsp vanilla extract
• 2 tbsp cold water
• 1½ tsp unflavored gelatin powder
• 1½ cup heavy cream divided, (360 ml)
• 4 large egg whites
• ¼ tsp cream of tartar
• ¼ cup granulated sugar 50 grams

Ganache

• 1 cup chopped dark chocolate 170 grams
• ½ cup chopped milk chocolate 85 grams
• 1 cup heavy cream 240 ml
• 1 tbsp corn syrup

Instructions

 

Chocolate Cake Batter

• This recipe utilizes my Chocolate Birthday Cake batter! Start by pre-heating the oven to 350ºF. Grease and line with parchment two 9-inch cake pans. Grease the parchment and the sides of the pan as well.
• In a large mixing bowl, mix the flour, sugar, cocoa powder, baking powder, baking soda, salt, and espresso powder (if using). Whisk to combine.
• In another bowl, combine the eggs, vegetable oil, buttermilk, sour cream, and the vanilla extract. Whisk until completely incorporated.
• Pour the wet ingredients over the dry ingredients and whisk until combined. When the batter is incorporated, add the hot coffee and mix to combine.
• Whisk until the batter is smooth. The chocolate cake batter will be very thin and liquidy.
• I like to transfer it to a bowl with a spout to help distribute the cake batter between the cake pans, which helps with such a runny batter.
• Divide the batter evenly between the cake pans. Tap them gently against the counter to release any bubbles.
• Bake the cakes in the oven for about 30 to 35 minutes, until a toothpick inserted into the cake comes off clean.
• Let the cakes cool down for 15 minutes in the pan.
• Then remove the cakes from the pan. Let them cool down completely before the next step. If you aren’t assembling the cake on the same day, I recommend you wrap each layer individually in plastic wrap and then freeze until you are ready to use the cake layers. When you are ready to assemble the cake, you can simply use the frozen cake layers, or let them sit on the counter for 20 minutes before beginning.

Preparing the Chocolate Mousse (Mise en place)

• Get all the ingredients separated and measured out, but keep the cream in the fridge so it remains cold.
• You will need a large bowl for the chocolate/egg yolk mixture. You will need a small bowl for heating up the cream with the gelatin. Another large bowl to whip the cream, and one more bowl to whip the egg whites.

Chocolate & Egg Yolks

• Place the chocolate in a large bowl. Microwave for 15 to 30 second intervals, stirring in between, until the chocolate melts completely.
• Allow for the chocolate to cool down for about 5 minutes.
• Add the yolks to the chocolate one at a time, whisking until incorporated. The mixture will get very thick and might get hard to whisk so you may have to use a spatula instead.
• Add the salt and vanilla, mix to combine. Set aside.

Gelatin

• Place the water in a small bowl. Sprinkle the gelatin powder over the water and let it sit for a couple of minutes.
• Meanwhile heat up 1/2 cup of the heavy cream in the microwave until hot and steaming.
• Pour the bloomed gelatin in the hot cream and stir to combine until the gelatin has dissolved with the hot cream.
• Pour the hot cream mixture over the chocolate/yolk mixture just a little at a time, stirring with a spatula until incorporated before adding the next little bit.
• Set the chocolate/yolk/gelatin mixture aside.

Whipped Cream

• Place the remaining 1 cup of cold heavy cream in a large bowl or in the bowl of a stand mixer. Whip on medium-high speed for a few minutes with the whisk attachment or with a hand mixer until stiff peaks form. Set it aside.

Egg Whites

• Place the egg whites and cream of tartar in a bowl, or in the bowl of a stand mixer. With the whisk attachment, whip until it becomes whitened in color and foamy. Then start adding the sugar while whisking on medium speed. Gradually add the sugar in until it’s all been added and continue to whip until stiff peaks form.

Assembling the Mousse

• Add half of the whipped cream to the chocolate/gelatin mixture and fold to combine.
• Add the remaining half and fold again.
• Add half of the whipped whites and fold gently.
• Add the remaining whipped whites and fold until incorporated.
• The mousse will be very runny, it’s ok, it will firm up in the fridge once you assemble the cake.

To Assemble the Cake

• You will need a large (9-inch, or adjustable) pastry ring and acetate to assemble the cake. If you don’t have a pastry ring, you can use a springform pan, but then I recommend halving the mousse recipe because you will have too much mousse and won’t be possible to form such a tall cake in the springform pan. Alternatively, you can make the full mousse recipe and divide whatever mousse doesn’t fit in the pan between ramekins and serve them like that.
• The acetate is needed for the recipe to work otherwise the mousse will leak out.
• Place a cake layer on the bottom of the pastry ring, or in the bottom of the springform pan with the acetate around it. You will want to leave a bit more loose at the top part so the top cake layer can slide in easily.
• Pour the mousse in, on top of the cake. Top with another cake layer.
• Place it in the fridge overnight, or at least 8 hours.

Chocolate Ganache

• To make the ganache place the chopped chocolate in a large bowl.
• Heat up the heavy cream and corn syrup until steaming.
• Pour the heavy cream and corn syrup over the chopped chocolate.
• Let it sit for one minute. Whisk until the chocolate has melted entirely.
• If the chocolate hasn’t melted, microwave for 10 to 15 second intervals, stirring in between until it melts, be careful not to overheat, or it can cause the ganache to split.
• Let the ganache sit at room temperature for about 1 hour until it thickens.

To Decorate

• Remove the pastry ring from around the cake. Carefully peel off the acetate.
• Spread the ganache over the cake. Decorate with berries and chocolate shavings if desired.

Notes

Coffee: Adding hot coffee not only enhances the chocolate flavor but also ensures a moist and rich cake. If you don’t have coffee, hot water with a pinch of espresso powder works well.

Chocolate: Use high-quality chocolate for the mousse; it will make a big difference in flavor. A combination of milk and dark chocolate creates a perfect balance of sweetness and richness.

Acetate sheets: They are essential for creating smooth edges and preventing the mousse from leaking. You can find acetate online or at baking supply stores, or online.

Pastry ring: If you don’t have a pastry ring, a springform pan with acetate works well, but consider halving the mousse recipe to avoid overflow. Or divide any leftover mousse that doesn’t fit in the cake between small ramekins.

Nutrition

Serving: 1sliceCalories: 650kcal

Keyword chocolate cake, chocolate mousse cake, mousse cake

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