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

Combine 100g of dark or semi-sweet chocolate and 50g of cocoa powder in a heatproof bowl and melt over a double boiler or microwave, stirring frequently until smooth.

In a saucepan, melt 230g of unsalted butter over medium heat until it turns golden brown and develops a nutty aroma, about 5-7 minutes. Pour over the chocolate mixture and stir to combine.

Whisk together 4 large eggs with 150g of granulated sugar and 100g of brown sugar until frothy, about 3-4 minutes. Then mix in the cooled chocolate-butter mixture.

Fold in 100g of all-purpose flour into the batter until just combined, being careful not to overmix.

Pour the batter into the prepared baking pan and bake for 28-30 minutes, until a toothpick comes out mostly clean with a few moist crumbs.

Remove the brownies and let cool on a wire rack for about 1 hour.

Beat 250g of mascarpone cheese until smooth and gradually add 200g of whipping cream, 50g of powdered sugar, and 0.5 tsp of vanilla extract until thick.

In a shallow dish, combine 2 tsp of espresso powder with 150g of hot water and 1 tbsp of coffee liqueur (if using). Dip ladyfingers quickly into the mixture.

Place the soaked ladyfingers atop the cooled brownies, then spread the whipped mascarpone mixture over them.

Cover and refrigerate for at least 1 hour to let the flavors meld and the cream set.

Dust the top with cocoa powder before serving, slice into squares, and enjoy.