Preheat your oven to 350°F (175°C) and line a 9x9-inch baking pan with parchment paper.

Melt 230g of unsalted butter in a saucepan over medium heat until golden brown and nutty, about 5-7 minutes. Pour it over 100g of dark or semi-sweet chocolate and 50g of cocoa powder in a mixing bowl, stirring until smooth.

In a large bowl, whisk together 4 large eggs with 150g of granulated sugar and 100g of brown sugar until pale and thick, about 2-3 minutes. Mix in the cooled chocolate mixture, then fold in 100g of all-purpose flour until just incorporated.

Pour the brownie batter into the baking pan and bake for 28-30 minutes. Let them cool in the pan on a wire rack.

In a mixing bowl, whip 250g of cold mascarpone cheese with 200g of heavy whipping cream and 50g of powdered sugar until light and creamy, about 3-5 minutes.

Combine 2 teaspoons of espresso powder with 150g of hot water. Briefly soak the ladyfingers in the espresso mixture, then layer them on top of the cooled brownie base.

Spread the mascarpone cream over the soaked ladyfingers and smooth it out.

Cover the pan with plastic wrap and refrigerate for at least 1 hour. Dust with cocoa powder before serving.