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!

Slice of three layer chocolate mousse cake on a white plate with a forkful missing.

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.

Recipe ingredients with labels on a white surface.

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.

Wet and dry cake ingredients stirred together in a mixing bowl.

Step 1: Make the cake. Whisk together dry ingredients. Add milk, oil, sour cream, egg, and vanilla. Stir until well combined.

Cake batter in a glass mixing bowl with a whisk.

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.

Hand whisking egg mixture in the bowl of a double boiler.

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.

Chocolate mixture in a mixing bowl with a whisk.

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.

Chocolate mousse mixture after whipped egg whites are folded in.

Step 6: Beat egg whites and sugar until stiff peaks form. Fold the whipped egg whites into the chocolate mixture.

Chocolate mousse after whipped cream is folded in.

Step 7: Beat heavy cream until stiff peaks form. Fold the whipped cream into the chocolate mixture.

Hand holding an offset spatula and spreading mousse over chocolate cake in a springform pan.

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.

Chocolate ganache in a small glass bowl with a spatula.

Step 9: Make the ganache. Add chocolate to a heat-safe bowl. Pour warmed cream over the chocolate. Stir the ganache until smooth.

Hand holding an offset spatula spreading ganache over the cake.

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.

Side view of chocolate ganache dripping down the side of a chocolate mousse cake on a white marble plate.

Recipe 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.

Overhead view of a slice of chocolate mousse cake on its side on a white marble plate.

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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