Preheat your oven to 350°F (175°C) and line an 8 or 9-inch square baking tin with parchment paper.

In a microwave-safe bowl, melt dark chocolate and unsalted butter together in 30-second intervals until smooth.

Stir in brown sugar and granulated sugar until fully incorporated, then add vanilla extract.

Add eggs one by one, whisking after each addition until the batter is glossy.

Sift in flour and salt, folding gently to combine without overmixing.

Pour the batter into the prepared tin and bake for 25 to 30 minutes until set around the edges.

Remove brownies and poke holes all over the surface, then pour freshly brewed espresso over the warm brownies.

Whisk mascarpone cheese, heavy cream, and vanilla in a separate bowl, then blend in espresso powder and powdered sugar until stiff peaks form.

Spread the mascarpone topping evenly over the cooled brownies.

Dust with cocoa powder, cut into squares, and serve immediately.