01 -
Preheat oven to 175°C and line a 20×20 cm baking pan with parchment paper. Whisk together melted butter, granulated sugar, eggs, and vanilla until smooth. Sift in cocoa powder, flour, salt, and baking powder. Gently fold dry ingredients into wet ingredients until just combined. Pour batter into prepared pan, smooth with spatula, and bake for 20-25 minutes until a toothpick comes out with a few moist crumbs. Cool completely in pan.
02 -
Heat milk until steaming but not boiling. Pour over chopped chocolate in a heatproof bowl. Let sit for 2 minutes, then stir until fully melted and smooth. Cool to room temperature. In a separate bowl, whip heavy cream with powdered sugar until soft peaks form. Gently fold cooled chocolate mixture into whipped cream until fully incorporated. Spread mousse evenly over cooled brownie base. Refrigerate for at least 2 hours until set.
03 -
Place chopped chocolate in a heatproof bowl. Heat heavy cream until simmering, then pour over chocolate. Let sit for 2-3 minutes, then stir until smooth and glossy. Pour ganache over set mousse layer and spread evenly with an offset spatula. Refrigerate for another hour until ganache firms.