This dark chocolate mousse cake brings together layers of tender cocoa-rich cake, silky chocolate mousse, and glossy ganache that pools just right when you slice into it. I first made this for my sister Karla's birthday three years ago, and she still asks for it every January. It takes a little time, but the process is straightforward, and you can do most of it ahead. If you love deep chocolate flavor without being too sweet, this one's for you. The mousse stays light and airy between those soft cake layers, and the ganache adds just enough richness to make each bite feel special.
You might also enjoy my Chocolate Chip Cookie Cake Recipe for a simpler celebration dessert, or try the Oatmeal Lemon Crumble Bars when you want something fruity to balance out all this chocolate. For another layered treat, the Best Pecan Pie Lasagna is always a crowd favorite.
Why You'll Love This Dark Chocolate Mousse Cake
The mousse filling makes this Dark Chocolate Mousse Cake feel fancy, but you don't need pastry school skills to pull it off. Everything comes together with basic mixing and folding, and the ganache is just two ingredients stirred smooth. You can bake the Dark Chocolate Mousse Cake layers a day early and keep them wrapped, then assemble when you're ready. It feeds a crowd without much fuss, and it holds up beautifully in the fridge for days. The cocoa flavor is deep and grown-up, not candy-bar sweet, which makes it perfect for birthdays, anniversaries, or any time you want to impress without stressing.
Jump to:
Dark Chocolate Mousse Cake Ingredients
Here's everything you need to make this rich, layered Dark Chocolate Mousse Cake.
See Recipe Card Below This Post For Ingredient Quantities
For the Cake:
- All-purpose flour: Forms the structure and keeps the cake tender without being too dense.
- Granulated sugar: Sweetens the cake and helps create a soft crumb.
- Unsweetened natural cocoa powder: Brings deep, earthy chocolate flavor that isn't overly sweet.
- Espresso powder: Enhances the chocolate taste without making it taste like coffee. You can skip it if you don't have any.
- Baking soda: Works with the acidic ingredients to help the cake rise and stay light.
- Baking powder: Adds extra lift for a fluffy texture.
- Salt: Balances the sweetness and makes the chocolate flavor pop.
- Full-fat sour cream: Adds moisture and a slight tang that keeps the cake from tasting flat.
- Vegetable oil: Creates a soft, moist crumb that doesn't dry out.
- Large eggs: Bind everything together and add richness.
- Buttermilk: Tenderizes the cake and adds a subtle tang. If you don't have buttermilk, mix milk with a splash of vinegar and let it sit for five minutes.
- Pure vanilla extract: Rounds out the chocolate flavor with warmth.
- Hot water or black coffee: Thins the batter and intensifies the cocoa. Hot water works fine if you don't want to make coffee.
- Semi-sweet mini chocolate chips: Optional, but they add little pockets of melty chocolate throughout the cake. Tossing them in flour keeps them from sinking.
For the Chocolate Mousse:
- Hot water: Helps dissolve the cocoa powder smoothly.
- Unsweetened natural or Dutch-process cocoa powder: Adds rich chocolate flavor to the mousse base.
- Quality semi-sweet chocolate: Melts into the mousse for silky texture and deep flavor. Chop it finely so it melts evenly.
- Heavy cream: Whips up light and airy, creating the mousse's signature fluffiness.
- Confectioners' sugar: Sweetens the mousse without making it grainy.
- Pure vanilla extract: Adds a hint of warmth that complements the chocolate.
For the Chocolate Ganache:
- Quality semi-sweet chocolate: The main flavor of the ganache. Finely chopped pieces melt faster and smoother.
- Heavy cream: Combines with the chocolate to create a glossy, pourable topping that firms up as it cools.
Optional Garnish:
- Fresh berries and/or chocolate shavings: Add color and a little tartness to balance the richness.
How to Make Dark Chocolate Mousse Cake
Follow these steps to build your Dark Chocolate Mousse Cake from start to finish.
Preheat oven: Preheat your oven to 350°F (177°C). Grease four 8-inch or 9-inch cake pans, line the bottoms with parchment paper rounds, then grease the parchment too so nothing sticks.
Make the cake: In a large bowl, whisk together the flour, sugar, cocoa powder, espresso powder, baking soda, baking powder, and salt until everything's evenly mixed. Set that aside. In another large bowl, use a handheld or stand mixer to beat the sour cream, oil, and eggs on medium-high speed until smooth and combined. Add the buttermilk and vanilla, then mix again until blended.
Combine wet and dry ingredients: Add the dry ingredients to the wet ingredients, then pour in the hot water or coffee. Mix on low speed until the batter looks smooth and pourable. If you're using mini chocolate chips, toss them with a tablespoon of flour first, then gently fold them into the batter.
Bake: Divide the batter evenly among your prepared pans. Bake for 19 to 23 minutes, or until a toothpick inserted in the center comes out clean or with just a few moist crumbs. The tops should look set and spring back lightly when touched.
Cool: Let the cakes cool in the pans for about 1 hour. Run a knife around the edges to loosen them, then turn them out onto a cooling rack. Let them cool completely before assembling, or they'll melt the mousse.
Make chocolate mousse: In a small bowl, whisk the hot water and cocoa powder together until smooth with no lumps. Melt the chopped chocolate in a double boiler or microwave, stirring every 20 seconds until silky. Stir the cocoa mixture into the melted chocolate and set it aside to cool slightly. In a separate bowl, whip the cold heavy cream, confectioners' sugar, and vanilla on medium-high speed until you see medium peaks form. Gently fold the chocolate mixture into the whipped cream using a spatula, working slowly so you don't deflate it. Cover and refrigerate for at least 2 hours until it firms up.
Assemble the cake: If your cake layers have domed tops, level them with a serrated knife so they stack evenly. Place the first layer on your serving plate or cake stand. Spread about 1.5 cups of mousse over the top, smoothing it gently. Add the second layer, then more mousse. Repeat with the third layer and mousse. Spread a thin layer of mousse over the top and around the sides as a crumb coat to seal in any loose crumbs. Refrigerate for at least 1 hour to set.
Make ganache: Heat the heavy cream in a small saucepan over medium heat, stirring occasionally. Once it starts to simmer and tiny bubbles form around the edges, pour it over the chopped chocolate in a heatproof bowl. Let it sit for 2 to 3 minutes without stirring, then whisk until smooth and glossy. Refrigerate for 30 minutes to 1 hour until it thickens slightly but stays pourable.
Finish the cake: Once the ganache has thickened, pour it over the chilled cake, starting in the center and letting it drip down the sides naturally. Use an offset spatula to smooth the top and sides if needed. Add fresh berries or chocolate shavings on top if you like.
Serve: You can serve the cake right away, or chill it for another 4 to 6 hours for cleaner slices. Store any leftovers covered in the refrigerator for up to 5 days.
Substitutions and Variations
Buttermilk: If you don't have buttermilk, mix ½ cup of milk with ½ tablespoon of white vinegar or lemon juice. Let it sit for 5 minutes before using.
Coffee: You can use hot water instead of black coffee if you prefer. The coffee enhances the chocolate but isn't necessary.
Cocoa powder: Dutch-process cocoa will give you a darker color and slightly milder flavor. Natural cocoa has a brighter, fruitier taste.
Chocolate: Use good-quality chocolate bars chopped up instead of chocolate chips for the Dark Chocolate Mousse Cake and ganache. The melting texture is smoother.
Sour cream: Greek yogurt works in a pinch, though the flavor will be a little tangier.
Pan size: You can use three 9-inch pans instead of four 8-inch pans. The layers will be thicker, and you may need to adjust baking time by a minute or two.
Equipment For Dark Chocolate Mousse Cake
- 8-inch or 9-inch round Dark Chocolate Mousse Cake pans: Four pans if you want thinner layers, or three if you prefer thicker ones.
- Glass mixing bowl: For combining ingredients and whipping cream.
- Whisk: Keeps dry ingredients evenly mixed and helps dissolve cocoa powder.
- Handheld or stand mixer: Makes quick work of beating the batter and whipping cream.
- Cooling rack: Lets air circulate around the cakes so they cool evenly.
- Double boiler or microwave-safe bowl: For melting chocolate smoothly without scorching.
- Cake stand or turntable: Makes it easier to spread mousse and ganache evenly.
- Large icing spatula: Smooths mousse and ganache with clean, even strokes.
- Bench scraper: Helps you get sharp edges and smooth sides.
- Cake carrier: Optional, but handy for storing the finished Dark Chocolate Mousse Cake without messing up the top.
Storage Tips For Dark Chocolate Mousse Cake
Refrigerator: Store the finished Dark Chocolate Mousse Cake covered in the fridge for up to 5 days. The mousse and ganache hold up well, and the flavors actually deepen after a day or two.
Freezer: You can freeze the baked Dark Chocolate Mousse Cake layers wrapped tightly in plastic wrap and foil for up to 3 months. Thaw them in the fridge before assembling. The assembled cake can be frozen for up to 1 month, but let it thaw slowly in the fridge overnight before serving.
Make-ahead: Bake the Dark Chocolate Mousse Cake layers a day ahead and keep them wrapped at room temperature. Make the mousse the same day you plan to assemble so it stays fresh and fluffy. The ganache can be made a few hours early and rewarmed gently if it gets too stiff.
Expert Tips
Room temperature ingredients: Make sure your eggs, sour cream, and buttermilk are at room temperature before mixing. Cold ingredients don't blend as smoothly and can make the batter lumpy.
Gentle folding: When you fold the melted chocolate into the whipped cream for the Dark Chocolate Mousse Cake, use a light hand and work slowly. Overmixing will deflate the cream and leave you with a dense mousse instead of a fluffy one.
Chill between steps: Don't rush the refrigeration times. The mousse needs to firm up before you assemble, and the crumb coat needs to set before you add the ganache, or everything will slide around.
Level your layers: Even if the cakes look mostly flat, leveling them with a serrated knife makes stacking easier and keeps the mousse from squishing out the sides.
FAQ
Is dark or milk chocolate better for mousse?
Dark chocolate gives you a richer, more intense flavor with less sweetness, which works beautifully in mousse. Milk chocolate makes it sweeter and milder, so it depends on what you're after. For this Dark Chocolate Mousse Cake, semi-sweet or dark chocolate keeps the mousse from tasting too sugary.
How to make Dark Chocolate Mousse Cake at home?
Melt quality dark chocolate, mix it with a little dissolved cocoa powder, then gently fold it into whipped cream. Chill it for a couple of hours to let it firm up. The key is folding slowly so you don't knock out all the air.
Do you have to use dark chocolate for mousse?
Not at all. You can use semi-sweet, milk, or even white chocolate depending on your taste. Just keep in mind that sweeter chocolates will make the Dark Chocolate Mousse Cake less intense and more dessert-like.
What are common mistakes when making mousse?
Adding the melted chocolate when it's too hot will deflate the whipped cream and leave you with a grainy texture. Overmixing does the same thing. Make sure your chocolate cools slightly before folding, and use a gentle hand when combining everything.
Related
Looking for other recipes like this? Try these:
Pairing
These are my favorite dishes to serve with Dark Chocolate Mousse Cake
Dark Chocolate Mousse Cake
Ingredients
Method
- Preheat the oven to 350°F (177°C). Grease four 8-inch or 9-inch cake pans, line with parchment paper rounds, then grease the parchment paper. Parchment paper helps the cakes seamlessly release from the pans.
- In a large bowl, whisk together the flour, sugar, cocoa powder, espresso powder, baking soda, baking powder, and salt. Set aside.
- In another bowl, combine the sour cream, oil, and eggs using a mixer or whisk. Beat on medium-high speed until well mixed. Add the buttermilk and vanilla, and mix until smooth.
- Slowly add the dry ingredients into the wet mixture, then pour in the hot water or coffee. Mix on low speed until just combined. Fold in the mini chocolate chips, if using. Divide the batter evenly among the prepared pans.
- Bake the cake layers for 19-23 minutes or until a toothpick inserted in the center comes out clean. Cool in the pans for 1 hour. Afterward, remove from pans and peel off the parchment paper. Place the cakes on a cooling rack to finish cooling.
- For the mousse, whisk the hot water and cocoa powder together in a small bowl until smooth. Melt the chopped chocolate using a double boiler or microwave in increments.
- Once melted, combine the hot water/cocoa mixture with the melted chocolate. Stir until thick and smooth. Set aside.
- In a large bowl, whip the cold heavy cream, confectioners' sugar, and vanilla until medium peaks form. Fold in the chocolate mixture gently. Do not overmix. Refrigerate the mousse for at least 2 hours or up to 2 days.
- Once the cakes have cooled, level the tops if needed. Place one cake layer on your serving plate, spread with 1.5 cups of mousse, then add the second layer upside down. Repeat the process, adding mousse between each layer. Finish by covering the entire cake with mousse.
- Refrigerate the cake for at least 1 hour or up to 4 hours to firm up.
- For the ganache, heat the cream over medium heat until it begins to simmer. Pour it over the chopped chocolate and let it sit for 2-3 minutes to soften. Stir until smooth. refrigerate for 30 minutes to 1 hour to thicken.
- Once thickened, pour the ganache over the chilled cake and smooth it out with a spatula. Garnish with fresh berries or chocolate shavings if desired.
- Serve immediately or chill for 4-6 hours before serving. The cake can be served at room temperature or chilled.
Leave a Reply