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Close-up of chocolate mousse brownies showing airy mousse texture, creamy center layer, and rich fudgy base with ganache topping.

Easy Chocolate Mousse Brownies

These Chocolate Mousse Brownies feature a rich fudgy brownie base, a light creamy mousse center, and a smooth ganache topping. This is our family’s favorite make-ahead dessert for birthdays, holidays, and cozy baking days together.
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Course: Dessert
Cuisine: American
Keyword: chocolate dessert bars, Chocolate Mousse Brownies, easy chocolate mousse brownies, fudgy brownies recipe, layered brownies
Prep Time: 20 minutes
Cook Time: 35 minutes
Chilling Time: 2 hours
Total Time: 2 hours 55 minutes
Servings: 12 servings
Calories: 420kcal
Cost: $14

Equipment

  • 1 9x13-inch baking pan Line with parchment for easy lifting
  • 1 Electric mixer For whipping the mousse
  • 1 Medium saucepan For butter and ganache
  • 1 Mixing bowls One for each layer
  • 1 Offset spatula Helps spread the mousse and ganache
  • 1 Sharp knife Clean cuts for perfect layers

Ingredients

For the Brownie Base

  • 1 cup unsalted butter melted
  • 2 cups granulated sugar
  • 4 large eggs room temperature
  • 1 tablespoon vanilla extract
  • ¾ cup unsweetened cocoa powder Dutch-processed preferred
  • 1 cup all-purpose flour
  • ½ teaspoon salt
  • ½ teaspoon baking powder

For the Chocolate Mousse

  • 8 ounces semi-sweet chocolate chopped
  • 2 cups heavy whipping cream divided
  • 3 tablespoons powdered sugar
  • 1 teaspoon vanilla extract

For the Ganache

  • 1 cup semi-sweet chocolate chips
  • ½ cup heavy whipping cream

For Garnish

  • Chocolate curls or shavings
  • Optional: cocoa powder for dusting

Instructions

  • Preheat the oven to 350°F (175°C). Line a 9x13 pan with parchment paper. This is Olivia’s favorite job, she makes sure the paper fits perfectly while I melt the butter.
  • Melt the [butter], then whisk in the [sugar] until glossy and smooth. Olivia always peeks into the bowl and says it looks like chocolate lava.
  • Whisk in the [eggs] one at a time, then stir in [vanilla]. Olivia counts the eggs out loud every time, she insists it helps the brownies rise.
  • Fold in [cocoa powder], [flour], [salt], and [baking powder] just until combined. I remind Olivia not to overmix, this keeps the brownies fudgy.
  • Bake for 25–30 minutes until a toothpick shows moist crumbs. Cool completely before adding mousse. Olivia patiently guards the counter to make sure nobody touches them early.
  • Heat ½ cup [cream] and pour over [chocolate]. Let cool to room temp. Whip remaining [cream] with [powdered sugar] and [vanilla], then gently fold in the chocolate. Olivia calls this “fluffy cloud magic.
  • Spread mousse over cooled brownies. Chill 2 hours until set. This is when Olivia checks the fridge every ten minutes like it’s ticking down to dessert time.
  • Heat [cream], pour over [chocolate chips], stir smooth. Pour gently over mousse and chill another hour
  • Slice with a clean knife, garnish with chocolate curls, and enjoy. Olivia always insists on cutting her own square, slightly crooked but full of pride.

Notes

  • For gluten-free, substitute flour with a 1:1 gluten-free baking blend.
  • For mint chocolate mousse brownies, add ½ teaspoon peppermint extract to the mousse.
  • Store covered in the refrigerator for up to 5 days.
  • These brownies taste even better the next day after the layers fully set.
  • Delicious served with fresh strawberries or vanilla ice cream.

Nutrition

Serving: 1brownie | Calories: 420kcal | Carbohydrates: 45g | Protein: 6g | Fat: 26g | Saturated Fat: 15g | Polyunsaturated Fat: 2g | Monounsaturated Fat: 7g | Cholesterol: 95mg | Sodium: 160mg | Potassium: 210mg | Fiber: 3g | Sugar: 35g | Vitamin A: 180IU | Calcium: 60mg | Iron: 2.4mg