• Preheat an oven to 180c (350f) and prep a parchment paper-lined 8 by 8 baking pan.
• In a large mixing bowl, add the butter and the dark chocolate. Melt completely in the microwave or on a bain Marie.
• Into the melty chocolate mixture, add the granulated sugar, brown sugar, cocoa powder (sifted), espresso powder, vanilla extract, and kosher salt, and mix with a whisk until well combined.
• Add the eggs and egg yolk and mix until well combined and smooth.
• Sift the flour and fold the mixture with a rubber spatula until the batter is almost combined.
• Pour the batter into a parchment paper lined 8 by 8 brownie pan and top with more chocolate chunks. Bake in a 180c (350f) preheated oven for 30-35 minutes. Do not overbake it to keep it fudgy!
• Allow the brownies to cool for at least 30 minutes before slicing, so they won't crumble and fall apart. 

For the mascarpone cream

• Into a large mixing bowl, add the heavy cream, vanilla extract, and powdered sugar and mix with an electric hand mixer until stiff peaks form. (don't overbeat the mixture so you don't create butter)
• Add the mascarpone cheese (which is at room temperature) and mix it lightly into the whipped cream using a spatula until a creamy mixture forms.
• Do not overmix this mixture! Stop just when the mixture is creamy and smooth. If you overmix this, the mixture will curdle and lose its creaminess.

Assembly

• Dip the ladyfingers in the coffee and layer them over the brownie layer. Top the ladyfinger layer with the mascarpone cream and smooth it out using an offset spatula.
• Cover the brownies with plastic wrap and leave in the fridge for at least 3 hours, overnight is better.
• Remove the brownies from the fridge and top with a generous layer of cocoa powder. Slice and enjoy.