Chocolate Mousse Brownies: Make-Ahead Dessert

Instructions:

1. Preheat your oven to 350°F (175°C). In a large bowl, whisk the 1/2 cup (115g) melted butter and 1 cup (200g) granulated sugar until the mixture looks glossy and smooth.
2. Add the 2 large eggs and 1 tbsp vanilla extract. Whisk vigorously for 2 full minutes until the batter lightens in color and becomes ribbony. Note: This step is vital for the crinkle top.
3. Sift in 1/2 cup (45g) Dutch cocoa powder, 1/2 cup (65g) all purpose flour, and 1/4 tsp salt. Use a spatula to fold gently until no white streaks of flour remain.
4. Pour the batter into your lined pan. Bake for 25 minutes until a toothpick comes out with a few moist crumbs attached. Note: Do not overbake; they will firm up as they cool. Let the base cool completely in the pan.
5. In a small microwave safe bowl, combine 1.5 cups (255g) semi sweet chocolate chips and 1/2 cup (120ml) of the heavy cream. Heat in 30 second bursts, stirring until the mixture is velvety and fully melted. Stir in 1/2 tsp espresso powder and let it cool to room temperature.
6. In a separate chilled bowl, beat the remaining 1.5 cups (360ml) heavy cream and 1/4 cup (30g) powdered sugar until stiff peaks form that don't slump over. This is very similar to the technique used in this How to Make recipe.
7. Gently fold the cooled chocolate mixture into the whipped cream. Use a slow, circular motion until the color is uniform and the mousse looks fluffy. Be careful not to deflate the air you just whipped in!
8. Spread the mousse evenly over the cooled brownies. Top with 1 tbsp chocolate shavings and a light dusting of 1 tsp cocoa powder. Chill for at least 4 hours until the mousse is set and firm to the touch.