Chocolate Mousse Cake

This Chocolate Mousse Cake recipe is the perfect cake for chocolate lovers. It's a delicious, rich, and creamy dessert cake that suits any occasion. It consists of a chocolate cake layer filled with chocolate mousse and topped with chocolate ganache. Doesn't that sound irresistible? By the way, have you tried my chocolate cream pie yet?

Jump to:

• Why You Will Love This Chocolate Mousse Cake Recipe
• Ingredients
• Substitutions
• Step-by-Step Video Tutorial
• How to Make Chocolate Mousse Cake
• Expert Tips for Success
• Recipe FAQs
• More Chocolate Cake Recipes to Try
• Recipe

Why You Will Love This Chocolate Mousse Cake Recipe

• Decadent Dark Chocolate Cake: This cake has it all! A thin layer of rich dark chocolate cake, a fluffy chocolate mousse, and finally a rich, thick chocolate ganache.
• A Dark Chocolate Mousse Cake For All Occasions: From elegant birthday cakes to Valentine's Day celebrations, or dinner parties!
• Perfect for Chocolate Lovers: Anyone who adores the bittersweet goodness of chocolate is going to love this Belgian Chocolate Mousse Cake Recipe.

Love chocolate desserts? You've got to try this Flourless Chocolate Cake next!

Ingredients

Here's a look at the key ingredients for making this triple chocolate mousse cake. Be sure to see the recipe card further down the page for the full list and quantities of each.

• Heavy whipping cream: This is the key to a rich, creamy chocolate mousse for the cake. Do not try to swap it for half and half or whole milk as you will not get the same results.
• Egg yolks: The mousse uses egg yolks and you will also need a whole egg for the cake. Save the egg whites to use to make an Angel Food Cake later on.
• Sugar: You will be using both granulated white sugar and powdered sugar. The powdered sugar for the mousse should be sifted prior to adding so you don't end up with any lumps.
• Chocolate bars: Choose a high-quality semi-sweet chocolate bar to make the chocolate mousse and ganache.
• All-purpose flour: Be sure to spoon the flour into the measuring cup and level it off with the flat side of a knife.
• Cocoa powder: The cake uses Dutch-processed cocoa powder. Like the flour it should be spooned into the measuring cup and leveled off with a knife.
• Vegetable oil: Any neutral-flavored vegetable oil works great.
• Buttermilk: The acid in the buttermilk plays a key role in the cake. Do not try to replace it with regular milk. If you don't have buttermilk you can make buttermilk using milk and lemon juice or vinegar. Add a scant teaspoon of vinegar or lemon juice to a liquid measuring cup and then add milk up to the ¼ cup line. Let it sit for five minutes.
• Hot cocoa: Hot cocoa is just unsweetened cocoa powder and boiling hot water. You typically need 1 teaspoon of cocoa powder per ¼ cup (60 mL) of water, but you can check the package directions to see if there is any. Do not use hot chocolate or sweetened cocoa as this would change the texture and flavor of the cake layer.

Substitutions

• Using Natural Unsweetened Cocoa Powder: The cake layer is made with Dutch-processed cocoa powder and baking powder. If you want to use natural unsweetened cocoa powder use the same amount of Dutch processed in the recipe. However, instead of 1 ½ teaspoons of baking powder, use ¾ teaspoon baking powder and ¼ teaspoon of baking soda.
• Hot Cocoa: You can also use the same amount of hot water in place of the hot cocoa for the cake and add an extra teaspoon of cocoa powder to the batter.

Step-by-Step Video Tutorial

How to Make Chocolate Mousse Cake

Step 1: Making the Chocolate Custard for the Mousse

• Step 1: Whisk together the heavy cream, egg yolks, and sugar in a medium saucepan.
• Step 2: Cook the mixture over medium-high heat whisking continuously until it thickens and coats the back of a spoon.
• Step 3: Remove from the heat and continue whisking for about 1-2 minutes. Add the melted chocolate to the pot. 
• Step 4: Whisk until mixed together. Transfer the chocolate custard to a large mixing bowl and let it cool completely.

Step 2: Mixing the Chocolate Cake

• Step 1: Combine the flour, cocoa, sugar, baking powder, and salt in a medium bowl. 
• Step 2: Whisk it together and set aside. 
• Step 3: Add the oil, egg, buttermilk, and vanilla to a mixing bowl or stand mixer. Beat it together until combined. 
• Step 4: Add the dry ingredients and stir them to combine. 

• Step 5: Slowly mix in the hot cocoa until well combined. The batter will be thin. 
• Step 6: Pour the batter into your greased and lined baking pan and bake in a preheated oven until the cake is done. 

Step 3: Adding the Whipped Cream to the Mousse

• Step 1: Beat the remaining heavy whipping cream in a large mixing bowl using a stand mixer or electric mixer until soft peaks form. 
• Step 2: Add the powdered sugar and beat until stiff peaks form.
• Step 3: Stir about a quarter of the whipped cream into the cooled chocolate cream until the mixture is smooth and combined.
• Step 4: Fold the remaining whipped cream into the chocolate mixture with a spatula carefully until it’s combined. Don't overwork the mousse or it won't set properly.

• Step 5: Pour the chocolate mousse into the pan over the top of the cake and spread evenly. Chill in an airtight container in the refrigerator overnight.

Step 4: Making the Chocolate Ganache

• Step 1: Place the chopped chocolate in a large heatproof bowl and the heavy cream in another heatproof bowl. Microwave the heavy cream until very hot, almost boiling. Pour it over the chocolate and let it stand for 1-2 minutes. 
• Step 2: Whisk the mixture until it’s smooth and the chocolate has completely melted. Chill in the fridge for about 10-15 minutes to thicken. 

PRO TIP: Test the consistency of the ganache on the side of the bowl. It should drip. The longer it cools, the thicker it gets. If it's too firm, reheat it in the microwave for a few seconds.

Step 5: Assemble the Cake

• Step 1: Spoon the ganache around the edges of the cake, letting it drip down the sides. Do this slowly with a small spoon, making a drop at a time. 
• Step 2: Spoon or pour the rest of the ganache frosting onto the cake (you may not need all of it) and smooth it with an offset spatula. 

• Step 3: Place the cake in the fridge for 15 minutes to allow the ganache to set. Decorate as you like. Store in an airtight container in the refrigerator for up to 3 days.

Expert Tips for Success

• Measure Dry Ingredients Properly. This is key for the best outcome of your chocolate cake layer. If you're not using a kitchen scale, fluff the dry ingredient up, scoop it into the measuring cup with a spoon, and then level it with the back of a knife without packing. If you don't measure the dry ingredients correctly, the cake layer can become dry and hard.
• Do Not Over-Bake. The cake layer is very thin and over-bakes quickly.
• Cool Completely. Allow the cake base to cool completely before filling it with the chocolate mousse so the mousse will set properly.
• Don't Boil the Egg Yolk Mixture. When making the mousse you want to heat it slowly or you might up with either scrambled eggs or the chocolate custard may split.
• Choosing Chocolate. Use only high-quality chocolate bars for the mousse instead of chocolate chips. The chocolate custard base for the mousse could become grainy and crumbly if you use use chips instead of chocolate bar.
• Folding the Chocolate Into the Whipped Cream. Stop folding the whipped cream into the chocolate custard as soon as it is combined. Don't overmix it or it won't set properly.
• Chill Before Serving. Make sure you chill the cake in the fridge for at least 4 hours before serving as it needs time to set and chill properly. Do not put it in the freezer to speed up the cooling process.

Recipe FAQs

More Chocolate Cake Recipes to Try

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