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Rich and decadent fudgy chocolate mousse brownies, perfect for satisfying any sweet craving.

Ultimate Fudgy Brownie Mousse

Indulge in the ultimate dessert experience with these Fudgy Brownie Mousse squares. A rich, fudgy brownie base is topped with a light and airy chocolate mousse, creating a decadent and unforgettable treat.
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Prep Time 45 minutes
Cook Time 30 minutes
Total Time 1 hour 15 minutes
Servings: 12
Course: Dessert
Cuisine: American
Calories: 450
Ingredients Equipment Method Notes

Ingredients
  

  • 8 ounces bittersweet chocolate, chopped 60-70% cacao
  • 1 1/2 cups granulated sugar
  • 1/2 cup packed brown sugar
  • 3 large eggs
  • 1 teaspoon vanilla extract
  • 1 cup all-purpose flour
  • 1/2 cup unsweetened cocoa powder Dutch-processed preferred
  • 1/4 teaspoon salt
  • 1/2 cup chopped walnuts or pecans optional
  • 1 1/2 cups cold heavy cream
  • 6 ounces bittersweet chocolate, chopped 60-70% cacao
  • 2 large eggs, separated
  • 1/4 cup granulated sugar
  • 1/2 teaspoon vanilla extract
  • Pinch of salt

Equipment

  • 9x13-inch baking pan
  • Parchment paper (optional)
  • mixing bowls
  • Heatproof bowl
  • Saucepan
  • Electric mixer or whisk
  • rubber spatula
  • measuring cups and spoons
  • toothpick
  • sharp knife
  • Plastic wrap

Method
 

  1. Preheat oven to 350°F (175°C). Grease and flour a 9x13 inch baking pan, or line with parchment paper.
  2. In a heatproof bowl set over simmering water (or in the microwave in 30-second intervals), melt butter and 8 ounces of bittersweet chocolate, stirring until smooth. Remove from heat and let cool slightly.
  3. Stir in 1 1/2 cups granulated sugar and 1/2 cup brown sugar until well combined.
  4. Add 3 eggs one at a time, beating well after each addition. Stir in 1 teaspoon vanilla extract.
  5. In a separate bowl, whisk together flour, cocoa powder, and salt.
  6. Gradually add dry ingredients to wet ingredients, mixing until just combined. Do not overmix.
  7. If using nuts, fold them in gently.
  8. Pour batter into prepared pan and spread evenly. Bake for 25-30 minutes, or until a toothpick inserted into the center comes out with moist crumbs attached. Underbake slightly for a fudgy texture.
  9. Let brownies cool completely in the pan.
  10. For the mousse, melt 6 ounces of bittersweet chocolate in a heatproof bowl set over simmering water (or in the microwave in 30-second intervals) until smooth. Remove from heat and let cool slightly.
  11. Separate 2 eggs, placing yolks in one bowl and whites in another.
  12. In a medium bowl, whisk egg yolks and 1/4 cup granulated sugar until pale and thick.
  13. Slowly whisk the cooled melted chocolate into the egg yolk mixture until well combined.
  14. In a separate bowl, whip heavy cream until stiff peaks form.
  15. In a clean, dry bowl, beat egg whites with a pinch of salt until stiff, glossy peaks form.
  16. Gently fold about 1/3 of the whipped cream into the chocolate mixture to lighten it. Then, gently fold in the remaining whipped cream and the whipped egg whites until just combined. Be careful not to deflate the egg whites.
  17. Once the brownie base has cooled completely, spread the chocolate mousse evenly over the top.
  18. Cover the pan with plastic wrap and chill in the refrigerator for at least 2 hours, or preferably overnight.
  19. Before serving, cut the brownies into squares using a warm, sharp knife.
  20. Optional: Garnish with cocoa powder, chocolate shavings, fresh berries, or a drizzle of melted chocolate.

Notes

For the best flavor and texture, use high-quality chocolate and do not overbake the brownies. Chilling the assembled brownies is crucial for the mousse to set properly. Store leftover brownies in an airtight container in the refrigerator for up to 3 days. Consider adding a tablespoon of instant espresso powder to the brownie batter to enhance the chocolate flavor.