Print

Chocolate Mousse Brownies Recipe

5 from 85 reviews

Delight in these decadent Chocolate Mousse Brownies featuring a rich, fudgy brownie base topped with a luxuriously smooth chocolate mousse. Perfectly baked to have set edges with a slightly underbaked center, these brownies are finished with a creamy, fluffy mousse made from melted chocolate, mini marshmallows, and whipped cream, then chilled to perfection. Ideal for chocolate lovers looking for an indulgent dessert that combines intense chocolate flavor with airy mousse texture.

Ingredients

Scale

Brownie Base

  • 4 ounces semisweet chocolate baking bar, chopped
  • ¼ cup salted butter
  • ⅓ cup vegetable oil
  • 1 ½ cups granulated sugar
  • 2 eggs, room temperature
  • 2 teaspoons pure vanilla extract
  • ¾ cup all purpose flour, spooned and leveled
  • ½ cup unsweetened dutch processed cocoa powder
  • ½ teaspoon baking powder
  • ½ teaspoon table salt

Chocolate Mousse

  • 4 ounces semisweet chocolate baking bar, chopped
  • 1 cup mini marshmallows
  • ¼ cup whole milk
  • 1 tablespoon whole milk
  • 1 ¼ cup cold heavy cream
  • Chocolate syrup for drizzling, optional garnish

Instructions

  1. Prepare Brownie Base: Preheat the oven to 350°F (175°C) and line a 9×9 inch baking pan with parchment paper, leaving an overhang for easy removal later.
  2. Melt Chocolate and Butter: In a microwave-safe bowl, melt the semisweet chocolate and butter together in 20-second intervals, stirring until smooth, or use a double boiler. Stir in vegetable oil until fully combined.
  3. Combine with Sugar: In a large mixing bowl, add granulated sugar and whisk in the warm chocolate mixture until thick and fully blended.
  4. Add Eggs and Vanilla: Whisk in eggs one at a time just until incorporated—avoid overbeating to prevent adding extra air. Stir in vanilla extract for flavor.
  5. Sift Dry Ingredients: Sift together flour, cocoa powder, baking powder, and salt over the wet mixture, then gently fold until the batter is uniform with no dry streaks.
  6. Bake Brownies: Spread the batter evenly in the prepared pan and bake for 22-25 minutes or until the edges are set but the center remains slightly underbaked for fudgy texture. Allow to cool completely in the pan.
  7. Chill Mixer Components: Place your mixing bowl and whisk attachment or beaters in the freezer to chill while preparing the mousse.
  8. Melt Chocolate and Marshmallows: In a medium saucepan over low heat, combine chopped chocolate, mini marshmallows, and ¼ cup whole milk. Stir constantly until melted and smooth. Remove from heat and let cool to room temperature to avoid deflating the whipped cream.
  9. Whip Cream: In a large bowl, beat the cold heavy cream until soft peaks form using an electric mixer.
  10. Combine Mousse Mixture: Lower mixer speed to low and add the cooled chocolate mixture to the cream, then increase speed and beat to stiff peaks. Be careful not to overwhip.
  11. Assemble: Spread the mousse evenly over the cooled brownies using a spatula. Cover tightly and refrigerate for at least 2 hours to set.
  12. Serve: Remove from refrigerator, slice into 12 equal squares, and optionally drizzle with chocolate syrup. Keep refrigerated until serving.

Notes

  • You can substitute regular unsweetened cocoa powder for Dutch-processed cocoa, understanding it will create a lighter-colored brownie.
  • Light brown sugar can replace granulated sugar if you prefer a chewier brownie texture.
  • These brownies can be chilled overnight before slicing and serving for convenience and enhanced flavor melding.

Keywords: chocolate mousse brownies, fudgy brownies, chocolate dessert, baked chocolate dessert, mousse topping, holiday brownies, American dessert bars