This white chocolate mousse cake is a true showstopper! A chewy, deeply chocolatey cake base is topped with a light, airy white chocolate mousse that gets covered in a silky chocolate ganache.
The combination of chewy, fluffy, and smooth textures makes every bite totally luxurious.
A cousin to the chocolate raspberry mousse cake, this is a dual-flavored tuxedo cake version. It's a nicely sweet white chocolate mousse with three distinct layers and flavors of chocolate.
While this cake uses a chewy brownie base, you can swap for a light and fluffy chocolate cake base like in this triple chocolate cake, chocolate walnut cake, or chocolate cream cheese cake.
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Why You'll Love This Recipe
Perfectly balanced layers -This cake is all about contrast with a dense, chewy chocolate cake base, a light and airy white chocolate mousse, and a silky-smooth ganache. Every bite leaves you longing for more!
Simple yet impressive - While it looks like it came straight out of a bakery, this cake is surprisingly simple to make! Each layer is straightforward, and there’s no need for fancy decorating skills. Just pour the ganache over the top and leave it as is or throw on some chocolate curls. It's the perfect cake for special occasions like birthdays or holidays.
Make ahead dessert - this cake needs to set in the fridge for a number of hours, and is served cold from the fridge, making it the perfect cake to make ahead of time (up to 3 days in advance)!
Ingredients
- Cocoa powder. Use dutch-processed cocoa powder for a balanced chocolate flavor and deep color.
- Semi-sweet chocolate. A good quality chocolate bar gets mixed into the cake and is also used for the chocoalte ganache. Look for something that's 60-70% cacao.
- Eggs. This cake doesn't have any leaveners (baking soda or baking powder), so eggs ensure that the cake rises slightly, but also remains chewy.
- White chocolate. This is the main flavor in the white chocolate mousse, so use a tasty bar like Ghirardelli or Lindt.
- Gelatin. This is what sets the white chocolate mousse layer! The recipe uses an unflavored, powdered gelatin.
- Heavy whipping cream. Gets whipped to stiff peaks and folded into the white chocolate ganache to create a light, airy layer.
See recipe card for full ingredients list and quantities.
Substitutions and Variations
- Cocoa powder. Use natural cocoa or black cocoa in place of dutch-processed cocoa.
- White chocolate mousse. Swap white chocolate for milk or dark chocolate or split the mousse layer in half and do two different chocolate layers for a classic triple chocolate mousse cake.
- Extra garnish. Top with chocolate shavings, berries, or candied citrus for a festive touch.
How to Make This Recipe
Chocolate Brownie Cake
One: Melt together the butter and chocolate until smooth.
Two: Beat the eggs and sugars until light and fluffy.
Three: Mix the melted chocolate and butter into the eggs and sugar.
Four: Sift in the cocoa powder and flour.
Hot tip! Cocoa powder is prone to clumping, so it's best to sift it in to get a smooth cake batter.
Five: Fold the batters together until smooth.
Six: Add the batter into a parchment-prepared springform pan and smooth it out, then bake and cool completely.
White Chocolate Mousse
Seven: Sprinkle the gelatin on top of water to bloom for a few minutes.
Eight: Mix the gelatin into hot cream until dissolved, then pour it over chopped white chocolate.
Nine: Mix until smooth and combined.
Ten: Whip remaining heavy cream until stiff peaks form.
Eleven: Fold ⅓ of the whipped cream into the cooled white chocolate ganache to lighten it up.
Twelve: Fold in the remaining whipped cream until smooth and combined.
Finishing the Cake
Thirteen: Add the white chocolate mousse onto the cooled cake layer and smooth it out. Refrigerate for a few hours to set.
Fourteen: Mix together hot cream and semi-sweet chocolate to create a thin chocolate ganache. Cool 10 minutes.
Hot tip! Use an offset spatula to create a very smooth mousse layer.
Fifteen: Pour the chocolate ganache all over the cake, getting down the sides.
Sixteen: Top the cake with a ring of chocolate and white chocolate curls before slicing in and enjoying.
Expert Tips
- Fully line the bottom and sides of the springform pan with parchment paper so you can create clean layers. Watch how to line a springform pan!
- Chill the mousse fully before adding ganache to make sure it holds its structure.
- Use quality white chocolate for the best flavor in every layer.
- Add the cake to a wire rack on top of a sheet pan to catch the chocolate drips.
- Smooth the sides with an offset spatula to help with coverage. A lot also builds up on top, so push some from the middle over the sides.
- Clean off the knife completely in between each slice for nice, clean slices.
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Recipe FAQs
Yes! You can make the entire cake a day in advance. Just store it in the refrigerator and add the ganache before serving for the best texture.
Use a sharp knife and wipe it clean between slices. Running the knife under warm water before slicing will help cut through the mousse smoothly.
This can happen if the whipped cream wasn’t fully whipped to soft peaks or if the chocolate mixture was still too warm when mixed in. Make sure to cool it properly before folding.
Storage
Store the cake in an airtight container or cover it with plastic wrap and keep it in the refrigerator for up to 4 days.
You can freeze the cake (without ganache) for up to 2 months. Wrap the cake tightly in plastic wrap, then aluminum foil, and place it in a freezer-safe container. When ready to serve, thaw overnight (uncovered) in the fridge and add the ganache before serving.
For the best texture, let the cake sit at room temperature for 10-15 minutes before serving.
What to Know When Cooking with The Cozy Plum
- All recipes are created with Diamond Crystal kosher salt, the least salty variety of kosher salt. If using Morton's, you'll need to cut the amount of salt in half as it's 2x as salty. This will be the same for sea salt. Please do not use table salt.
- Switch between Cups vs Metric using the toggle on the recipe card. Baking by weight using a digital scale will always produce the most accurate results.
- Scale the recipe using the '1X' '2X' '3X' buttons on the recipe card. Note that this does not make an adjustment for baking times, only quantities.
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📖Recipe
White Chocolate Mousse Cake
Equipment
Ingredients
Chocolate Cake
- ¾ cup unsalted butter room temperature
- 2 oz semi-sweet chocolate chopped (60-70% cacao)
- ¾ cup granulated sugar
- ½ cup light brown sugar packed
- 3 large eggs room temperature
- ½ teaspoon kosher salt
- ½ cup all-purpose flour
- ½ cup Dutch processed cocoa powder
White Chocolate Mousse
- 1 ½ teaspoons powdered gelatin
- 2 tablespoons water
- 12 oz white chocolate chopped
- 1 cup heavy whipping cream cold
- 2 cups heavy whipping cream cold
Chocolate Ganache
- 6 oz semi-sweet chocolate chopped (60-70% cacao)
- 1¼ cups heavy whipping cream
Instructions
Chocolate Cake
- Preheat the oven to 350℉ and grease and line one 9″ round springform pan with parchment paper. Coat the entire inside with a thin layer of nonstick spray, then cover the bottom with a round sheet of parchment paper and line the sides with additional strips of parchment paper.
- Note: The cake will stick to the sides of the pan otherwise, so make sure the entire inside is covered in parchment paper.
- In a microwave-safe bowl, add the butter and chopped chocolate. Melt in 30 second intervals, stirring in between each, until smooth. Set aside.¾ cup unsalted butter, 2 oz semi-sweet chocolate
- In a large mixing bowl, add the sugars, eggs, and salt. Whisk (using a hand mixer or by hand) vigorously for three minutes until frothy.Pour in the cooled chocolate mixture and whisk until combined.¾ cup granulated sugar, ½ cup light brown sugar, 3 large eggs, ½ teaspoon kosher salt
- Sift in the flour and cocoa powder and use a rubber spatula to mix it in until just combined.½ cup all-purpose flour, ½ cup Dutch processed cocoa powder
- Scrape the batter into the prepared springform pan, spread evenly, then bake for 25-30 minutes. Cool completely.
White Chocolate Mousse
- In a small bowl, sprinkle the gelatin over the water; let stand for 5 minutes. Add the white chocolate to a medium bowl and set aside.1 ½ teaspoons powdered gelatin, 2 tablespoons water, 12 oz white chocolate
- Bring 1 cup of the heavy cream to a simmer in a small saucepan over medium-high heat. Remove from heat and whisk in the gelatin until dissolved.1 cup heavy whipping cream
- Pour the hot cream over the white chocolate and whisk until the chocolate is melted and the mixture is completely smooth. Cool to room temperature, about 10 minutes (the mixture will thicken slightly) – stir it every few minutes.
- While cooling, add the remaining 2 cups of heavy cream (cold) to the bowl of a stand mixer fitted with the whisk attachment (or use a hand mixer) and whip on medium speed until it starts to thicken, then increase to high speed and whip until soft peaks form.2 cups heavy whipping cream
- Whisk one-third of the whipped cream into the white chocolate mixture to loosen it up, then fold in the remaining whipped cream using a rubber spatula until completely incorporated.
- Pour the white chocolate mousse onto the cooled chocolate cake, smooth it out (an offset spatula helps with this) and add the cake in the fridge to let the mousse set (a minimum of 3 hours).
Chocolate Ganache
- Chop the chocolate and place it into a medium sized heat proof bowl.6 oz semi-sweet chocolate
- Heat the heavy cream in a saucepan or in the microwave until bubbles form around the edges and it begins to steam, then pour over the chocolate.1¼ cups heavy whipping cream
- Allow it to stand for one minute, then carefully stir until completely smooth.
- Note: if it seems grainy, thin, or not smooth, pop the bowl into the microwave for 30 seconds and stir it again.
- Let the ganache cool down, stirring occasionally, for about 10 minutes until it’s no longer hot, but still remains a thin, pourable consistency.
- Remove the cake from the springform pan. Carefully peel off the parchment from the sides and the bottom, then add the cake onto a wire rack with a 3-4" strip of parchment paper the entire way underneath it (so you have "handles" to move it). Place a sheet pan underneath to catch the chocolate ganache.
- Slowly pour the ganache over top of the cake starting from the center, being sure it covers the sides entirely.
- Note: use an offset spatula to smooth the chocolate over the sides where all of the chocolate may not have fully covered it. You can also move some of the chocolate from the top down over some of the sides that need more coverage.
- Once the ganache is done dripping and has set, use the parchment paper handles to transfer the cake to a serving platter, then gently slide it out. Clean up any dirty areas on the platter.
- Garnish with a ring of dark and white chocolate curls before slicing and serving.
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