Chocolate Mousse Brownies are a delightful treat that brings together the rich, fudgy texture of classic brownies with a light, airy chocolate mousse topping. The combination of dense, chewy brownie base with the smooth and creamy mousse on top makes every bite a perfect mix of indulgence and comfort. If you love chocolate, these brownies are sure to become one of your favorites.
I love making these for gatherings because they always get compliments and disappear fast! One of my favorite tricks is to chill them well before serving—the mousse firms up just right and makes the brownies even easier to slice neatly. Plus, you can play around by adding a sprinkle of sea salt on top to balance all that chocolate goodness. It’s a simple touch that really elevates the flavors.
These brownies are perfect when you want something special but don’t want to fuss too much. I like to serve them with a glass of cold milk or even a little fresh fruit on the side to add a bit of brightness. Whenever I make these, they bring out smiles and the feeling that something homemade with love is always the best kind of sweet treat.
Key Ingredients & Substitutions
Butter: Unsalted butter gives the brownies a rich, creamy base. You can swap it with coconut oil for a dairy-free version, but expect a slightly different texture.
Chocolate: Using good quality semisweet or bittersweet chocolate for both mousse and ganache really lifts the flavor. If you prefer milk chocolate, it works too, but the mousse will be sweeter and lighter.
Heavy Cream: It’s essential for whipping into the mousse and ganache. For a lighter mousse, you can use half-and-half, but it won’t whip as thick. Coconut cream can be a vegan substitute.
Cocoa Powder: Choose natural unsweetened cocoa for that deep chocolate taste. Dutch-processed cocoa works well too, just keep in mind the acidity affects leavening slightly.
How Do You Get a Smooth and Light Chocolate Mousse?
The mousse needs gentle folding to keep it airy. Here’s how:
- Heat cream just until almost boiling, then pour over chopped chocolate. Let it sit before stirring to melt smoothly.
- Whip the cold cream separately until soft peaks form; don’t overbeat or it will get grainy.
- Fold the whipped cream gently into the melted chocolate mixture using a spatula. Use slow, circular motions to keep the air in the mousse.
- Chill the mousse for at least 2 hours to let it set firmly but stay light.
I like to taste a tiny bit of mousse before chilling—it should feel smooth, not dense. This step is key to avoid a heavy or grainy topping!
Equipment You’ll Need
- 8-inch square baking pan – I use this to keep the brownies neat and easy to cut.
- Mixing bowls – for preparing the brownie batter, mousse, and ganache; a must-have for organization.
- Measuring cups and spoons – precise measurement helps get the perfect texture and flavor.
- Microwave-safe bowl or saucepan – for melting butter and chocolate smoothly.
- Whisk or electric mixer – makes whipping the cream and mixing ingredients quick and easy.
- Rubber spatula – perfect for folding in the whipped cream and spreading layers evenly.
- Cool rack – for cooling brownies without getting soggy, and for chilling the mousse and ganache.
Flavor Variations & Add-Ins
- Swap semisweet chocolate for dark or milk chocolate depending on your taste preference. Dark adds richness, milk makes it sweeter.
- Add a splash of liqueur like Baileys or Grand Marnier to the mousse for a boozy twist that adults will love.
- Mix in chopped nuts (walnuts, pecans) into the brownie layer for crunch and extra flavor.
- Swirl in a spoonful of peanut butter or caramel into the mousse before chilling for an extra treat.
How to Make Chocolate Mousse Brownies
Ingredients You’ll Need:
For the Brownie Layer:
- 1/2 cup (115g) unsalted butter
- 1 cup (200g) granulated sugar
- 2 large eggs
- 1 teaspoon vanilla extract
- 1/3 cup (35g) unsweetened cocoa powder
- 1/2 cup (65g) all-purpose flour
- 1/4 teaspoon salt
- 1/4 teaspoon baking powder
For the Chocolate Mousse Layer:
- 1 1/2 cups (360ml) heavy whipping cream, divided
- 6 oz (170g) semisweet or bittersweet chocolate, finely chopped
- 2 tablespoons powdered sugar
- 1 teaspoon vanilla extract
For the Chocolate Ganache Topping:
- 3 oz (85g) semisweet chocolate, chopped
- 3 tablespoons heavy cream
For Garnish:
- Whipped cream
- Fresh raspberries
- Fresh mint leaves
- Chocolate shavings (optional)
How Much Time Will You Need?
Plan for about 15-20 minutes to prepare and bake the brownies, another 15 minutes to make the mousse and ganache, plus at least 2.5 hours chilling time (2 hours for mousse to set and 30 minutes for ganache to firm up). This recipe needs some patience but the delicious results are worth the wait!
Step-by-Step Instructions:
1. Bake the Brownie Layer:
Preheat your oven to 350°F (175°C). Grease an 8-inch square baking pan and line it with parchment paper, leaving an overhang for easy removal later. In a microwave-safe bowl, melt the butter, then stir in sugar until combined. Add eggs one at a time, whisking well after each. Stir in vanilla extract.
Sift in cocoa powder, flour, salt, and baking powder. Gently fold everything together just until mixed—avoid overmixing to keep brownies fudgy. Pour batter into the pan and spread evenly. Bake for 20-25 minutes or until a toothpick comes out with moist crumbs. Let brownies cool completely before adding mousse.
2. Make the Chocolate Mousse Layer:
Heat 1/2 cup (120ml) heavy cream until just about to boil. Remove from heat and add chopped chocolate. Let it sit for a minute, then stir until smooth. Allow this mixture to cool to room temperature.
In a separate bowl, whip the remaining 1 cup (240ml) heavy cream with powdered sugar and vanilla extract until soft peaks form. Gently fold the whipped cream into the cooled chocolate mixture until light and combined. Spread the mousse evenly over the cooled brownie layer. Chill in the fridge for at least 2 hours to set.
3. Prepare Ganache and Serve:
Heat 3 tablespoons heavy cream until simmering, then pour over chopped chocolate in a bowl. Let it sit 1-2 minutes before stirring until smooth. Pour ganache evenly over the set mousse layer and smooth the top. Chill again for 30 minutes to allow ganache to firm up.
When ready, slice the brownies into squares. Top each piece with whipped cream, a fresh raspberry, and a mint leaf. Sprinkle with chocolate shavings if you like. Serve chilled and enjoy your rich, creamy chocolate mousse brownies!
Can I Use Frozen Brownie Batter or Pre-Made Brownies?
It’s best to bake the brownies fresh for the best texture and flavor. However, if using pre-made or frozen brownies, make sure they are fully thawed and cooled before adding the mousse layer to prevent melting or sogginess.
How Long Can I Store Chocolate Mousse Brownies?
Store leftovers in an airtight container in the refrigerator for up to 3 days. Because of the mousse and ganache layers, chilling is important to keep them firm and fresh.
Can I Substitute Heavy Cream in the Mousse?
You can try using coconut cream for a dairy-free version, but the texture will be slightly different. Half-and-half or regular cream won’t whip as well and may result in a less stable mousse.
Is It Okay to Make This Dessert Ahead of Time?
Absolutely! These brownies actually taste better after chilling for several hours or overnight, as it allows the mousse and ganache to set perfectly and the flavors to meld.