• Steps

Step 1: Make the Brownie Base

• Preheat the oven to 350°F (175°C) and line an 8×8-inch (20×20 cm) baking pan with parchment paper. In a mixing bowl, whisk together the melted butter, granulated sugar, eggs, and vanilla extract until the mixture is smooth. Sift the cocoa powder, flour, salt, and baking powder into the wet ingredients, then gently fold everything together until just combined—avoid overmixing to keep the brownies tender. Pour the batter into the prepared pan and spread it evenly with a spatula. Bake for 20–25 minutes or until a toothpick inserted in the center comes out with a few moist crumbs. Allow the brownies to cool completely in the pan.

Step 2: Prepare the Chocolate Mousse

• Warm the milk in a small saucepan until it’s steaming but not boiling. Pour the hot milk over the chopped semisweet chocolate placed in a heatproof bowl. Let it rest for 2 minutes, then stir until the chocolate melts completely and becomes smooth. Allow the mixture to cool to room temperature, so it’s no longer warm but still pourable. In a separate bowl, whip the heavy cream with the powdered sugar until soft peaks form. Carefully fold the cooled chocolate mixture into the whipped cream, mixing gently to preserve the mousse’s light texture. Spread the mousse evenly over the cooled brownie base and refrigerate for at least 2 hours until set.

Step 3: Top with Ganache

• Place the chopped chocolate in a heatproof bowl. Heat the heavy cream in a small saucepan until it just starts to simmer, then pour it over the chocolate. Let the mixture sit for 2–3 minutes before stirring until smooth and glossy. Pour the ganache evenly over the mousse layer and spread it with an offset spatula. Chill the dessert in the refrigerator for another hour or until the ganache firms up.