This elegant triple chocolate mousse cake combines three layers of chocolate - moist chocolate cake, luscious chocolate mousse, and creamy chocolate ganache - into one over-the-top indulgent dessert. With a simplified process and ingredient list, this stunning dessert recipe is surprisingly straightforward to make at home!
Is there a more luxurious chocolate cake than a chocolate mousse cake?
With not one but three layers of chocolate, this beautiful cake is a chocolate lover's dream.
Other recipes that I found for chocolate mousse cake seemed overly complex and used tricky ingredients or equipment that I don't have in my home kitchen. Bloom gelatin for the mousse? No thanks! Assemble the cake using an acetate collar? Don't have one.
I knew that I wanted to create a simplified recipe that's just as indulgent but is easier to make at home.
This unfussy version pairs my beloved one-bowl chocolate cake recipe with a thick layer of chocolate mousse and a coating of creamy, two-ingredient chocolate ganache. It's just as uncomplicated as it is decadent, and it would make the perfect cake for a special celebration or date night at home!
Ingredient Notes & Substitutions
See recipe card at the bottom of this post for full ingredient list and measurements.
Cocoa Powder - Cocoa powder gives this cake its rich chocolate flavor. You can use natural unsweetened for a classic chocolate flavor, though I prefer Dutch process for a smooth dark chocolate flavor.
Brewed Coffee - We'll add hot coffee to the cake batter to help bloom the cocoa and amplify the chocolate flavor. We'll also add a little bit of cooled coffee to the mousse, again to enhance the chocolate flavor. You won't taste the coffee in the cake, but you will taste it a little bit in the mousse (it gives the mousse a subtle mocha flavor), and you can replace it with water if you prefer.
Eggs - This recipe uses an egg in the cake and egg yolks and whites separately in the mousse. The yolks are cooked and add thickness and creaminess to the mousse, while the whites are whipped and add lightness.
Chocolate Baking Bar - A chocolate baking bar is key to the flavor and texture of both the mousse and the ganache. You can find baking bars in the baking aisle at your local grocery store. Do not substitute chocolate chips, since they contain stabilizers that will affect the texture when melted.
Heavy Cream - We'll use heavy whipping cream in both the mousse and ganache. For the mousse, the cream is whipped to stiff peaks and adds both lightness and creaminess. For the ganache, the cream is warmed used to melt the chocolate into a pourable sauce. Be sure to buy heavy whipping cream, which has the proper fat content for whipping.
Special Equipment
I worked hard to keep the equipment needed as simple as possible for this recipe and figured out a way to stack the cake without using an acetate cake collar, since most home bakers (myself included) don't own one. That said, I do recommend some special tools for making this recipe.
- A 9 inch springform pan, for assembling the cake. In order to cleanly slice and serve the cake, you'll need a cake pan with a removable bottom.
- A double boiler, for cooking the egg yolks in the mousse. If you don't have one, my post about melting chocolate in a double boiler will teach you how to DIY a double-boiler using kitchen equipment you probably already own.
- An instant read thermometer, for confirming the temperature of the egg yolks. You can use visual cues when cooking the yolks if you don't have a thermometer, but a thermometer is helpful.
- An electric hand mixer, for whipping the egg whites and heavy cream in the mousse.
- An offset spatula, for spreading the mousse and ganache over the cake.
Step-By-Step Recipe Instructions
See recipe card at the bottom of this post for detailed recipe instructions.
Step 1: Make the cake. Whisk together dry ingredients. Add milk, oil, sour cream, egg, and vanilla. Stir until well combined.
Step 2: Add hot coffee to the batter, carefully mixing with a whisk until well blended.
Step 3: Pour the batter into a round cake pan sprayed with cooking spray and lined with a round of parchment. Bake at 350º F for 30-35 minutes. Let the cake cool completely.
Step 4: Make the mousse. In the bowl of a double boiler, cook egg yolks, brewed coffee, sugar, and salt, whisking constantly until it becomes lighter in color, doubles in volume, and reaches 160°F.
Step 5: Remove the bowl from the heat and add chocolate, whisking until the chocolate melts and the mixture is smooth. Let cool to room temperature.
Step 6: Beat egg whites and sugar until stiff peaks form. Fold the whipped egg whites into the chocolate mixture.
Step 7: Beat heavy cream until stiff peaks form. Fold the whipped cream into the chocolate mixture.
Step 8: Place the chocolate cake onto the base of a 9 inch springform pan and secure the band around the cake. Spoon the mousse onto the cake and use an offset spatula to spread it. Chill the cake and mousse for at least 3 hours.
Step 9: Make the ganache. Add chocolate to a heat-safe bowl. Pour warmed cream over the chocolate. Stir the ganache until smooth.
Step 10: Remove the band from the pan. Pour the ganache over the mousse and use an offset spatula to spread it over the top of the cake and just to the edges, allowing some to drip down the sides of the cake. Chill the cake for 30 minutes before slicing and serving.
Allison's Top Tips
When you brew the coffee for the cake, make extra and set it aside to cool for the mousse so that you only have to brew coffee once.
Finely chop the chocolate for the mousse and ganache so that it melts more easily.
Be sure the bowl and beaters you use to whip the egg whites are clean and grease-free or the whites won't whip properly.
For clean slices, wipe the knife off with a paper towel after each slice.
Garnish Ideas
Just about anything that pairs well with chocolate would be a beautiful garnish for this cake. Here are some ideas, but feel free to get creative!
- Dusting of cocoa powder, powdered sugar, or espresso powder
- Dollops of whipped cream
- Fresh fruit like raspberries, cherries, or sliced strawberries
- Chocolate curls
- Chocolate covered espresso beans
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Recipe
Triple Chocolate Mousse Cake
Special Equipment
- Springform pan (9 inch)
- double boiler (or a medium saucepan and heat-safe bowl for a DIY double boiler)
Ingredients
Chocolate Cake
- 1 cup (120 grams) all-purpose flour
- 1 cup (198 grams) granulated sugar
- ⅜ cup (32 grams) cocoa powder
- 1 teaspoon (4 grams) baking powder
- ¾ teaspoon (5 grams) baking soda
- ½ teaspoon (3 grams) fine sea salt
- 3 ounces (85 grams) whole milk
- ¼ cup (50 grams) vegetable oil
- 2 Tablespoons (28 grams) full-fat sour cream
- 1 large egg, lightly beaten
- 1 teaspoon (5 grams) vanilla extract
- ½ cup (114 grams) hot coffee
Chocolate Mousse
- 6 large egg yolks (save the whites)
- 3 ounces (85 grams) strong brewed coffee room temperature
- 4 ½ Tablespoons (56 grams) granulated sugar divided
- ⅛ teaspoon (0.75 grams) fine sea salt
- 9 ounces (255 grams) semisweet chocolate baking bar chopped
- 3 large egg whites
- ¾ cup (170 grams) heavy whipping cream chilled
Chocolate Ganache
- 6 ounces (170 grams) semisweet chocolate baking bar chopped
- 6 ounces (170 grams) heavy whipping cream
Instructions
- Preheat oven to 350º F. Spray a 9 inch round cake pan with cooking spray and line the bottom with parchment paper. Set aside.
Make the cake.
- In a large bowl, whisk together flour, sugar, cocoa powder, baking powder, baking soda, and salt.1 cup (120 grams) all-purpose flour, 1 cup (198 grams) granulated sugar, ⅜ cup (32 grams) cocoa powder, 1 teaspoon (4 grams) baking powder, ¾ teaspoon (5 grams) baking soda, ½ teaspoon (3 grams) fine sea salt
- To the dry ingredients add milk, oil, sour cream, egg, and vanilla. Stir until well combined. The batter will be thick, similar to the texture of brownie batter.3 ounces (85 grams) whole milk, ¼ cup (50 grams) vegetable oil, 2 Tablespoons (28 grams) full-fat sour cream, 1 large egg,, 1 teaspoon (5 grams) vanilla extract
- Add hot coffee to the batter, carefully mixing with a whisk until well blended. The batter will now be very thin.½ cup (114 grams) hot coffee
- Pour the batter into the prepared cake pan and bake for 30-35 minutes, or until the top sprigs back when gently poked and a cake tester inserted into the center of the cake comes out clean or with just a few moist crumbs. Let the cake cool completely in the pan on a wire rack.
Make the mousse.
- Place a small amount of water in the bottom of a double boiler (or a medium saucepan) and bring to a simmer. Place the bowl of the double boiler (or a medium heat-safe bowl) on top of the pan of simmering water, checking to make sure the bowl sits above and does not touch the water.
- In the bowl, combine the egg yolks, brewed coffee, 3 Tablespoons (37 grams) of the sugar, and salt. Cook the mixture, whisking constantly, until it becomes lighter in color and doubles in volume, about 5 minutes. An instant-read thermometer inserted into the mixture should read 160°F.6 large egg yolks, 3 ounces (85 grams) strong brewed coffee, 4 ½ Tablespoons (56 grams) granulated sugar, ⅛ teaspoon (0.75 grams) fine sea salt
- Remove the bowl from the pan of simmering water. Add the chocolate and whisk until the chocolate melts and the mixture is smooth. Let the mixture stand, whisking occasionally, until it cools to room temperature, about 30 minutes.9 ounces (255 grams) semisweet chocolate baking bar
- While the chocolate mixture cools, place the chocolate cake onto the base of a 9 inch springform pan. Place the band around the cake and close the clamp to secure it to the base. Set aside.
- In a large bowl, beat the egg whites using an electric hand mixer until they become foamy. With the mixer running on low speed, slowly add the remaining 1 ½ Tablespoons (19 grams) sugar to the foamy egg whites. Increase speed to high and beat the mixture until stiff peaks form.3 large egg whites
- Fold the whipped egg whites into the chocolate mixture, being careful not to deflate the mixture.
- In the same large bowl you used to whip the egg whites, beat heavy cream using an electric hand mixer until stiff peaks form.¾ cup (170 grams) heavy whipping cream
- Gently fold the chilled whipped cream into the chocolate mixture just until blended, again being careful not to deflate the mixture.
- Spoon the mousse over the top of the cake. Use an offset spatula to spread the mousse to the sides and smooth the top. Chill the cake and mousse in the fridge for at least 3 hours.
- Once chilled, take the cake out of the fridge. Remove the band from the around the cake by first running an offset spatula around the edge of the cake between the mouse and the pan, then opening the clamp and lifting the band up off the cake.
Make the ganache.
- Add the chopped chocolate to a medium heat-safe bowl and set aside.6 ounces (170 grams) semisweet chocolate baking bar
- Add the cream to a small saucepan and heat until just shy of simmering.6 ounces (170 grams) heavy whipping cream
- Pour the warmed cream over the chocolate and let it sit for 2 minutes. Then stir with a rubber spatula until the chocolate is completely melted and the mixture is smooth and shiny.
- Let the ganache cool very briefly, just 2-3 minutes. It should thicken ever-so-slightly but still be pourable. Then pour the ganache over the mousse and use an offset spatula to spread the ganache over the top of the cake and just to the edges, allowing some of the ganache to drip down the sides of the cake.
- Return the cake to the fridge for 30 minutes to let the ganache set. Slice and serve chilled.
mic says
ok ok ok , you win!
This will now be the ONLY cake recipe I need!
Winner winner chocolate cake dinner!
Deeeelicious and perfect.
So tall and feeds a crowd.
I thank you! (my hips don't....)
Allison Ferraro says
This review makes me so happy, Mic! Thanks for loving this cake as much as I do!
- Allison
Daniella says
Made this for NYE and was a hit with everyone! I made it the night before. The mousse set perfectly even sitting out for a few hours after serving the cake. Not runny at all. I followed your note using hot water instead of coffee (i used a bit of instant coffee only to enhance flavour) and it worked perfectly.
Crissy says
Omg! I made this for my father in laws birthday celebration! Every single layer of the cake turned out perfect! It was so beautiful and I was so proud of it! Perfect recipe!
Allison Ferraro says
Hi Crissy! Thanks so much for this awesome review! This cake is definitely one to be proud of, and I'm so glad to hear it was a hit for your father-in-law's birthday!
- Allison