Preheat your oven to 350°F (175°C). Line an 8 or 9-inch square baking tin with parchment paper, letting it hang over the edges.

In a microwave-safe bowl, combine the dark chocolate and unsalted butter. Microwave in 30-second increments, stirring after each session until smooth, about 1-2 minutes total.

Mix in the brown sugar and granulated sugar until well combined. Allow the mixture to cool slightly.

Stir in the vanilla extract and add eggs one at a time, whisking vigorously after each addition until fully incorporated.

Sift the all-purpose flour and a pinch of salt over the wet mixture. Gently fold the dry ingredients into the chocolate mixture using a spatula.

Pour the brownie batter into the prepared tin, smoothing the top with a spatula. Bake for 25-30 minutes, or until a toothpick comes out with a few moist crumbs.

Remove the brownies from the oven and poke holes all over the surface. Pour the two shots of espresso evenly over the warm brownies.

In a separate bowl, whisk the mascarpone cheese, heavy cream, and half a teaspoon of vanilla extract until smooth and combined.

Add the espresso powder and powdered sugar to the mascarpone mixture and whisk until stiff peaks form.

Spread the mascarpone topping evenly over the surface of the brownies once completely cool.

Dust the top of the mascarpone layer with cocoa powder using a sieve.

Lift brownies out of the tin using the parchment paper overhang. Cut into squares and serve.