Pull up a chair, friend. I baked something special that tastes like a cozy hug and looks like a celebration. These chocolate mousse brownies layer a deep, fudgy brownie base with a cloud of silky chocolate mousse, so every bite hits the chocolate lover’s sweet spot. I make chocolate mousse brownies for birthdays, potlucks, snow days, and any Tuesday that needs cheering up. They feel fancy, yet they use pantry staples and simple steps you can master on the first try.

Why You’ll Love This Recipe

Sarah

Irresistibly Rich Chocolate Mousse Brownies

Pull up a chair, friend. I baked something special that tastes like a cozy hug and looks like a celebration. These chocolate mousse brownies layer a deep, fudgy brownie base with a cloud of silky chocolate mousse, so every bite hits the chocolate lover’s sweet spot.

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Prep Time 30 minutes mins

Cook Time 30 minutes mins

3 hours hrs

Total Time 4 hours hrs

Servings: 12 bars

Course: Dessert

Cuisine: American

Calories: 367

Ingredients Equipment Method Notes

Ingredients

  

For the Brownie Layer

• 1 1/2 cups all-purpose flour For gluten-free, use a 1:1 baking blend.
• 1 tablespoon cornstarch Softens the crumb for an extra tender bite.
• 1/3 cup Dutch-processed cocoa powder Dutch gives deeper flavor; natural cocoa also works.
• 1/2 teaspoon baking powder Lifts the batter slightly for a fudgy-chewy texture.
• 1/4 teaspoon kosher salt Balances sweetness and boosts chocolate notes.
• 4 large eggs room temperature. Warmer eggs whip up thicker for shiny tops.
• 2 cups granulated sugar Sweetens and helps that classic crackly finish.
• 3/4 cup unsalted butter Melt it for max fudginess and a glossy top.
• 2 teaspoons vanilla extract Adds warmth and rounds out the cocoa.

For the Mousse

• 1 1/2 cups heavy whipping cream cold, divided. Cold cream whips best.
• 1 cup semi-sweet chocolate chips Use milk or dark to taste.

For Garnish (optional)

• Chocolate curls

Equipment

• 9×13 inch metal baking pan
• Parchment Paper
• large mixing bowl
• medium mixing bowl
• whisk
• silicone spatula
• hand mixer
• Stand mixer
• small saucepan
• Microwave-safe bowl
• offset spatula
• Sharp Knife

Method

 

Brownie Layer

1. Preheat the oven to 350°F. Line a 9×13-inch baking dish with parchment paper, leaving some overhang for easy removal of the brownies. Lightly grease the parchment.
2. In a large bowl, whisk flour, cornstarch, cocoa powder, baking powder, and salt until no cocoa lumps remain.
3. Melt the butter until fully liquid, then let it cool until warm, not hot. This step sets up the fudgy base for chocolate mousse brownies.
4. In another bowl, beat eggs and sugar on medium-high for 2 to 3 minutes until thick, pale, and ribbony. Beat in vanilla.
5. With the mixer on low, slowly pour in the melted butter. Mix until smooth and glossy, about 30 seconds. Do not overmix.
6. Add the dry mix to the wet mix. Fold gently with a spatula just until no dry streaks remain. The batter will be thick. Overmixing can make brownies cakey.
7. Spread batter into the prepared pan and smooth the top. Bake 22 to 26 minutes, until a toothpick comes out with a few moist crumbs but no wet batter. Slight underbaking keeps chocolate mousse brownies extra fudgy.
8. Set the pan on a rack and cool to room temperature, 1 to 2 hours. Cold layers mean clean, sharp mousse edges.

Mousse Layer

1. Heat 1/2 cup of the heavy cream until steaming, not boiling, on the stove or in the microwave. Pour over the chocolate chips in a bowl. Let stand 1 minute, then stir until smooth and glossy. If needed, microwave in 5 to 10 second bursts. Cool to barely warm, about 10 minutes.
2. In a chilled bowl, beat the remaining 1 cup cold heavy cream to medium peaks. When you lift the whisk, the peaks should hold but soften slightly at the tips. Do not whip to stiff peaks or the mousse can turn grainy.
3. Stir a big dollop of whipped cream into the chocolate to lighten it. Gently fold in the rest in 2 to 3 additions until no streaks remain. The mousse should look silky and airy.
4. Spread the mousse evenly over the cooled brownie layer with an offset spatula. Chill at least 2 hours until set. This rest gives chocolate mousse brownies clean slices and distinct layers.

Garnish and Serve

1. Add chocolate curls if you like. Lift the slab out by the parchment, then slice with a hot, wiped-dry knife. Share and enjoy.

Notes

Do not overbake: Pull the brownies when a toothpick shows moist crumbs for peak fudginess. Cool completely before topping: Warm brownies melt mousse. Keep cream cold: Cold cream whips faster and holds its structure. Let chocolate cool slightly: Hot chocolate deflates cream and can cause grainy mousse. Slice smart: Chill chocolate mousse brownies well, warm your knife, and wipe between cuts.

Refrigerate: Cover and refrigerate chocolate mousse brownies up to 4 days. Freeze: Freeze cut bars on a sheet until solid, then wrap and store up to 2 months. Thaw in the fridge. Make ahead: Bake the brownie base 1 day ahead, wrap and chill, then add mousse the day you serve. Clean cuts: Chill well, use a hot knife, and wipe after each slice.

Ingredients and Substitutions

Here is what you need for chocolate mousse brownies, plus smart swaps I trust in my kitchen.

• 1 1/2 cups (187.5 g) all-purpose flour. For gluten-free, use a 1:1 baking blend.
• 1 tablespoon cornstarch. Softens the crumb for an extra tender bite.
• 1/3 cup (39 g) Dutch-processed cocoa powder. Dutch gives deeper flavor; natural cocoa also works.
• 1/2 teaspoon baking powder. Lifts the batter slightly for a fudgy-chewy texture.
• 1/4 teaspoon kosher salt. Balances sweetness and boosts chocolate notes.
• 4 large eggs, room temperature. Warmer eggs whip up thicker for shiny tops.
• 2 cups (400 g) granulated sugar. Sweetens and helps that classic crackly finish.
• 3/4 cup (170 g) unsalted butter. Melt it for max fudginess and a glossy top.
• 2 teaspoons vanilla extract. Adds warmth and rounds out the cocoa.
• 1 1/2 cups (357 g) heavy whipping cream, cold, divided. Cold cream whips best.
• 1 cup semi-sweet chocolate chips. Use milk or dark to taste.
• Chocolate curls, optional for garnish.

Melted butter gives the brownies richness and chew without needing oil. Dutch cocoa amplifies chocolate flavor, while cornstarch keeps chocolate mousse brownies plush and tender. For another chocolate dessert to try, look into Tiramisu Brownies with Espresso Mascarpone Cream.

Equipment

Step-by-Step Instructions with Photos

How to Make Chocolate Mousse Brownies

1. Preheat the oven to 350°F. Line a 9×13-inch baking dish with parchment paper, leaving some overhang for easy removal of the brownies. Lightly grease the parchment. Photo: show lined pan with overhang.
2. Mix dry ingredients. In a large bowl, whisk flour, cornstarch, cocoa powder, baking powder, and salt until no cocoa lumps remain. Photo: smooth, evenly brown dry mix.
3. Melt and cool the butter. Melt the butter until fully liquid, then let it cool until warm, not hot. This step sets up the fudgy base for chocolate mousse brownies.
4. Whip eggs and sugar. In another bowl, beat eggs and sugar on medium-high for 2 to 3 minutes until thick, pale, and ribbony. Beat in vanilla. Photo: batter drips in a thick ribbon.
5. Stream in butter. With the mixer on low, slowly pour in the melted butter. Mix until smooth and glossy, about 30 seconds. Do not overmix.
6. Combine. Add the dry mix to the wet mix. Fold gently with a spatula just until no dry streaks remain. The batter will be thick. Overmixing can make brownies cakey.
7. Bake. Spread batter into the prepared pan and smooth the top. Bake 22 to 26 minutes, until a toothpick comes out with a few moist crumbs but no wet batter. Slight underbaking keeps chocolate mousse brownies extra fudgy. Photo: shiny, slightly domed surface.
8. Cool completely. Set the pan on a rack and cool to room temperature, 1 to 2 hours. Cold layers mean clean, sharp mousse edges.
9. Make the chocolate base for the mousse. Heat 1/2 cup of the heavy cream until steaming, not boiling, on the stove or in the microwave. Pour over the chocolate chips in a bowl. Let stand 1 minute, then stir until smooth and glossy. If needed, microwave in 5 to 10 second bursts. Cool to barely warm, about 10 minutes. Photo: velvety ganache. For more on different ways to make chocolate mousse, you can refer to this page.
10. Whip the cream. In a chilled bowl, beat the remaining 1 cup cold heavy cream to medium peaks. When you lift the whisk, the peaks should hold but soften slightly at the tips. Do not whip to stiff peaks or the mousse can turn grainy.
11. Fold the mousse. Stir a big dollop of whipped cream into the chocolate to lighten it. Gently fold in the rest in 2 to 3 additions until no streaks remain. The mousse should look silky and airy. Photo: marbled folds becoming uniform.
12. Top and chill. Spread the mousse evenly over the cooled brownie layer with an offset spatula. Chill at least 2 hours until set. This rest gives chocolate mousse brownies clean slices and distinct layers.
13. Garnish and serve. Add chocolate curls if you like. Lift the slab out by the parchment, then slice with a hot, wiped-dry knife. Share and enjoy.

Expert Tips for Success

• Do not overbake. Pull the brownies when a toothpick shows moist crumbs for peak fudginess.
• Cool completely before topping. Warm brownies melt mousse.
• Keep cream cold. Cold cream whips faster and holds its structure.
• Let chocolate cool slightly. Hot chocolate deflates cream and can cause grainy mousse.
• Slice smart. Chill chocolate mousse brownies well, warm your knife, and wipe between cuts.

Recipe Variations

• Mint-chocolate: Add 1/2 teaspoon peppermint extract to the mousse for festive chocolate mousse brownies.
• Raspberry swirl: Marble 1/3 cup seedless raspberry jam on the brownie batter before baking.
• Mocha vibe: Dissolve 1 teaspoon instant espresso in the hot cream for the mousse.
• Triple chocolate: Stir 1/2 cup white chocolate chips into the brownie batter.
• Salted crunch: Sprinkle flaky salt and crushed chocolate wafer cookies on top. If you’re also a fan of spiced desserts, try these Gingerbread Crinkle Cookies for a seasonal twist.

Storage and Make-Ahead Tips

• Refrigerate. Cover and refrigerate chocolate mousse brownies up to 4 days.
• Freeze. Freeze cut bars on a sheet until solid, then wrap and store up to 2 months. Thaw in the fridge.
• Make ahead. Bake the brownie base 1 day ahead, wrap and chill, then add mousse the day you serve.
• Clean cuts. Chill well, use a hot knife, and wipe after each slice.

Nutrition

These values are estimates for one of 16 bars of chocolate mousse brownies.

Conclusion

I hope you feel excited to bake, slice, and share these chocolate mousse brownies. They taste like a bakery treat, yet they come together with simple steps and a little patience. If you try them, leave a comment, ask questions, or share a photo so we can cheer you on. Your kitchen can absolutely turn out swoon-worthy sweets. Now grab a whisk, cue your favorite playlist, and let’s get a pan in the oven.

Frequently Asked Questions