Preheat the oven and line a baking pan with parchment paper.
Melt dark chocolate and butter together until smooth.
Whisk in sugar and eggs, then gently fold in flour and cocoa powder.
Pour the brownie batter into the prepared pan and bake until just set.
Allow brownies to cool completely.
Whip mascarpone cheese, heavy cream, powdered sugar, vanilla, and cooled espresso until creamy.
Spread the mascarpone mixture evenly over the cooled brownies.
Dust with cocoa powder and refrigerate before slicing and serving.
