Dark Chocolate Mousse Cake: A Rich and Airy Triple Layer Dessert with Silky Ganache

Name: Dark Chocolate Mousse Cake
Prep time: 1 h
Cook time: 24 min
Total time: 10 h 24 min
Ingredients: 1 Cup (120g) All-Purpose Flour; ½ Cup (42g) Dutch Cocoa Powder; 1 teaspoon Fine Espresso Powder; ¾ teaspoon Baking Powder; ½ teaspoon Baking Soda; ¼ teaspoon Fine Sea Salt; ¾ Cup + 2 Tablespoons (175g) White Granulated Sugar; ⅓ Cup + 1 Tablespoon (80g) Neutral Oil, avocado, vegetable, canola; ⅓ Cup (76g) Full-Fat Sour Cream, room temp; 1 Whole Large Egg, room temp; 1 teaspoon Pure Vanilla Extract; ½ Cup (113g) Boiling Water; 1 ½ Cups (340g) Heavy Cream; 1 Whole Large Egg; 1 Large Egg Yolk; ⅓ Cup (67g) White Granulated Sugar; ¼ Cup (21g) Dutch Cocoa Powder; 1 teaspoon Fine Espresso Powder; ⅛ teaspoon Fine Sea Salt; 6 Ounces (170g) Dark Chocolate, 60% to 70%; 1 teaspoon Pure Vanilla Extract; 1 Cup (227g) Heavy Cream (to be whipped), cold; 5 Ounces (141g) Dark Chocolate, 60% to 70%; ⅔ Cup (151g) Heavy Cream

By:

Gabriella Brotherton

Published:

October 10, 2026

[grow_share_buttons]

Jump to Recipe·Print Recipe

Dark Chocolate Mousse Cake

This dark chocolate mousse cake looks like a bakery showpiece, but it comes together in simple steps inside one springform pan.

A super moist chocolate cake base sits underneath a light and airy chocolate mousse made without gelatin, and a silky smooth dark chocolate ganache finishes the top. Every slice feels special, and it is surprisingly light for how decadent it tastes.

If you like playing with flavor, a raspberry mousse cake is a suggested variation. The recipe comes from Lisa Flinn’s dark chocolate mousse cake.

The Layers

The cake is built in three distinct parts, and each one brings something different to the plate.

The chocolate cake base is adapted from a chocolate cupcake recipe. It has a deeply rich chocolate flavor because it uses Dutch process cocoa powder, and it stays extremely moist even when served cold straight from the refrigerator. That matters here, because the finished cake lives in the fridge.

The dark chocolate mousse is light and airy and melts in the mouth. It contains no gelatin. Instead, eggs add richness and stability, and they are cooked directly in the saucepan, slow and low, along with the rest of the mousse mixture.

Dark Chocolate Mousse Cake, The Layers — Dark Chocolate Mousse Cake: A Rich And Airy Triple Layer Dessert With Silky Ganache 72

That is easier than tempering eggs the way you would for a custard style ice cream, and it keeps everything in one pot. An eggless version appears in the FAQ toward the end of the original post.

The dark chocolate ganache is silky smooth and, as the source describes it, irresistible. It ties the chocolate flavors together and gives every slice a glossy finish.

If a fruity twist sounds good to you, a raspberry mousse cake is the suggested flavor variation. These Dark Chocolate Raspberry Mousse Cakes are a lovely place to start.

Jump to:

Ingredient Notes

The notes below cover the cake and the mousse. Full quantities for all three components appear in the table further down, and the method is broken into simple steps later in this post.

For the chocolate cake:

All purpose flour: measure it with a kitchen scale. Adding too much flour turns the cake dry and dense instead of light and moist.
Dutch process cocoa powder: this one is required. Natural cocoa powder is acidic and would not work with the amount of leaveners in this recipe.
Leaveners: baking powder and baking soda are used together for the perfect rise and texture.
Fine espresso powder: enhances the chocolate flavor. It is optional, but highly recommended.
Fine sea salt: rounds out the flavors and balances the sweetness.
White granulated sugar: adds sweetness and moisture.
Neutral oil: makes the cake light and moist.
Full fat sour cream: adds moisture.
Whole egg: adds structure.
Vanilla paste or extract: adds flavor.
Boiling hot water: blooms the espresso and the cocoa powder.

For the chocolate mousse:

Dark Chocolate Mousse Cake, Ingredient Notes — Dark Chocolate Mousse Cake: A Rich And Airy Triple Layer Dessert With Silky Ganache 73

Heavy cream has two applications. It is first cooked with the chocolate mousse mixture, then whipped later and folded into the cooled mixture.
Whole egg plus one yolk: adds richness and helps thicken the mousse.
Sugar: lightly sweetens the mousse.
Dutch process cocoa powder: again, for deep chocolate flavor.
Fine espresso powder: enhances the chocolate flavor.
Dark chocolate: the source uses Ghirardelli 60% chocolate chips and recommends using between 60% and 70%. A chocolate bar works just as well.
Salt: enhances all the flavors.
Vanilla extract: adds flavor.

Full ingredient list at a glance

Component	Ingredient	Amount
Chocolate Cake	All purpose flour	1 cup (120g)
Chocolate Cake	Dutch process cocoa powder	½ cup (42g)
Chocolate Cake	Fine espresso powder (optional)	1 teaspoon
Chocolate Cake	Baking powder	¾ teaspoon
Chocolate Cake	Baking soda	½ teaspoon
Chocolate Cake	Fine sea salt	¼ teaspoon
Chocolate Cake	White granulated sugar	¾ cup plus 2 tablespoons (175g)
Chocolate Cake	Neutral oil, such as avocado, vegetable or canola	⅓ cup plus 1 tablespoon (80g)
Chocolate Cake	Full fat sour cream, room temperature	⅓ cup (76g)
Chocolate Cake	Whole large egg, room temperature	1
Chocolate Cake	Pure vanilla extract	1 teaspoon
Chocolate Cake	Boiling water	½ cup (113g)
Chocolate Mousse	Heavy cream	1 ½ cups (340g)
Chocolate Mousse	Whole large egg	1
Chocolate Mousse	Large egg yolk	1
Chocolate Mousse	White granulated sugar	⅓ cup (67g)
Chocolate Mousse	Dutch process cocoa powder	¼ cup (21g)
Chocolate Mousse	Fine espresso powder	1 teaspoon
Chocolate Mousse	Fine sea salt	⅛ teaspoon
Chocolate Mousse	Dark chocolate, 60% to 70%	6 ounces (170g)
Chocolate Mousse	Pure vanilla extract	1 teaspoon
Chocolate Mousse	Heavy cream, cold, for whipping	1 cup (227g)
Chocolate Ganache	Dark chocolate, 60% to 70%	5 ounces (141g)
Chocolate Ganache	Heavy cream	⅔ cup (151g)

One full recipe makes 9 servings.

Step By Step Instructions

Below you will find the step by step instructions for each component: the chocolate cake, the chocolate mousse, and the ganache. Plan for about 1 hour of prep time, 24 minutes of cook time, and 9 hours of cooling the mousse plus chilling the cake.

Most of that is hands off time in the refrigerator, so start this cake the day before you plan to serve it.

How to make Chocolate Cake

Start with the cake so it has plenty of time to cool.

Preheat the oven to 350ºF (180ºC). Grease and line a 9 inch (23cm) springform pan with parchment paper.
In a small mixing bowl, whisk together the flour, Dutch process cocoa powder, espresso powder, baking powder, baking soda and salt.
In a large bowl and using a hand whisk, whisk together the sugar, oil, sour cream, egg and vanilla until well combined.
Sift the dry ingredients into the wet ingredients, pushing any cocoa powder lumps through the sieve. Gently whisk until nearly incorporated. The batter will be thick at this point.
Add the boiling hot water and gently whisk until just combined. Do not overmix.
Pour the batter into the prepared pan and bake for 24 to 28 minutes, until an inserted toothpick comes out clean. The recipe card lists a cook time of 24 minutes, so keep an eye on your oven.
Cool on a wire rack for 15 minutes, then remove the cake from the pan and let it cool completely at room temperature or in the fridge.

Tip

For a flat, even cake layer, use a cake strip. If you do not have one, make your own by soaking a tea towel in cold water for about 15 minutes, wringing out the excess, and wrapping it snugly around the cake pan just before baking.

The damp strip regulates the pan temperature so the edges do not cook faster than the center.

How to Make Chocolate Mousse

In a small saucepan, and off the heat, whisk together the heavy cream, the whole egg, the yolk, the sugar, the cocoa powder, the espresso powder and the salt until well combined.
Set the pan over low heat and whisk constantly until the mixture reaches 170ºF (76ºC). This takes about 8 to 10 minutes.
Off the heat, add the dark chocolate and the vanilla and whisk until smooth and combined.
Transfer the chocolate mixture to a medium bowl and press a piece of plastic wrap directly on the surface to prevent a skin from forming. Chill for 1 to 1.5 hours, until thick and spreadable. If it hardens, let it sit on the counter until it softens a little.
While the mousse mixture chills, line the bottom of the springform pan with a fresh piece of parchment paper. If the cake top is domed, level it with a serrated knife. Place the cooled cake back into the pan and wrap the sides with a 29 inch (74cm) piece of acetate, taping the ends so it does not unravel. Parchment paper works too, lightly sprayed with oil.
In a large mixing bowl and using a hand mixer, whip the cold heavy cream until firm peaks. Do not overmix.
In 2 additions, gently fold the chocolate mixture and the whipped cream together until there are no more white streaks. Do not overmix.
Spread the chocolate mousse over the cake layer and chill for at least 8 hours.

Tip

A cake collar, meaning an acetate sheet, gives you cleaner sides. If you use parchment paper instead, lightly spray it with oil so the mousse releases more easily.

Dark Chocolate Mousse Cake, Tip — Dark Chocolate Mousse Cake: A Rich And Airy Triple Layer Dessert With Silky Ganache 82

When you are ready to serve, make the ganache. Place 5 ounces (141g) of finely chopped dark chocolate, 60% to 70%, or chocolate chips in a heatproof medium bowl.

In a small saucepan over medium heat, bring ⅔ cup (151g) heavy cream to a low simmer until it reaches about 185ºF (85ºC). Submerge the hot cream over the chocolate and let it stand untouched for 4 to 5 minutes.

Stir slowly with a silicone spatula until smooth and combined. If the chocolate has not completely melted, set the bowl of ganache over a small pot of simmering water and heat until completely smooth.

Remove the chilled cake from the fridge and unmold it from the pan. Peel off the acetate or parchment paper and slide the cake onto a serving plate. Pour the ganache on top and spread it to the edges with an offset spatula.

Before serving, you can place the cake back into the fridge for 10 to 15 minutes to let the ganache set, then slice and enjoy.

Substitutions

Cake, sour cream: replace with full fat Greek yogurt.
Cake, neutral oil: avocado oil, vegetable oil, canola oil, refined coconut oil or grapeseed oil all work well.
Cake, espresso powder: highly recommended, but it can be omitted completely if you do not have it. Hot coffee can be used in place of the hot water, and the boiling hot water can also be swapped for hot coffee.
Mousse, espresso powder: can be omitted if it is not on hand.
Mousse, dark chocolate: the source uses Ghirardelli 60% chips, and a chopped chocolate bar works just as well.

If you do not own a springform pan, bake the cake in a regular 9 inch (23cm) pan instead. Place the cooled cake on a serving platter and wrap it with a long sheet of acetate. It will be sturdy enough without needing to assemble the cake inside a pan.

Dark Chocolate Mousse Cake, Substitutions — Dark Chocolate Mousse Cake: A Rich And Airy Triple Layer Dessert With Silky Ganache 92

Storage

Store the cake covered in the refrigerator for up to 5 days. To freeze, wrap individual slices in plastic wrap. Once they are completely frozen, transfer them to freezer bags. Thaw in the fridge overnight or at room temperature before eating.

️ Expert Tips

Use a kitchen scale to weigh all ingredients. Baking in grams rather than by volume is the best and most accurate way to bake, and the gram conversions here follow King Arthur’s Weight Chart.
Use a cake strip for a flat cake layer, or make your own by dampening a tea towel with cold water and wrapping it around the cake pan.
When cooking the eggs for the chocolate mousse, keep the heat low and whisk continuously. Slow and low prevents scrambled eggs and keeps the mixture perfectly smooth.
Measure the flour carefully. A heavy hand with flour is the fastest route to a dry, dense cake instead of a light and moist one.
Let the mousse mixture chill until it is thick and spreadable before you fold it into the whipped cream.

♡ Did you try this recipe?

If you bake this dark chocolate mousse cake, consider leaving a 5 star rating and a review.

Reviews give useful feedback to the recipe’s author and to other readers who are deciding what to bake next. Happy baking.

More Cakes & Cupcakes

If you enjoy layered chocolate desserts, these are worth a look:

Each one takes a slightly different route to the same idea: chocolate, cream, and a little patience in the refrigerator.

FAQs

What is dark chocolate mousse cake made of?

It is built from three components: a moist chocolate cake base, an egg-based chocolate mousse, and a chocolate ganache. The cake uses all-purpose flour, Dutch-process cocoa powder, white sugar, neutral oil, full-fat sour cream, one whole egg, vanilla, and boiling water. The mousse combines heavy cream, one whole egg plus one yolk, sugar, Dutch cocoa powder, dark chocolate at 60% to 70%, and whipped cream, while the ganache is dark chocolate and heavy cream. One cake yields 9 servings.

How long does dark chocolate mousse cake need to chill?

The cooked mousse mixture chills in the refrigerator for 1 to 1.5 hours until thick and spreadable, and the assembled cake then chills for at least 8 hours. Total time from start to finish is about 10 hours 24 minutes, which includes 1 hour of prep and 24 minutes of baking. The full chill sets the mousse so the slices hold their shape.

How do you store dark chocolate mousse cake?

Keep the cake covered in the refrigerator for up to 5 days. To freeze it, wrap individual slices in plastic wrap, place the frozen slices in freezer bags, and thaw them overnight in the refrigerator or at room temperature before eating. The ganache may lose some of its gloss in the fridge, but the flavor stays excellent.

Why did my chocolate mousse not thicken?

Mousse often stays loose when the egg and cream mixture is not cooked long enough to activate the eggs. Whisk it constantly over low heat until it reaches 170°F (76°C), about 8 to 10 minutes, then chill it until thick and spreadable. Also whip the cold heavy cream to firm peaks and fold it in gently in two additions, because overmixing deflates the air.