Preheat the oven

• Preheat the oven to 170 °C and line a square tin with baking paper.

Brown the butter and melt the chocolate

• Brown the butter in a saucepan over medium heat until golden and nutty.
• Melt the chopped chocolate separately.
• Stir the butter and chocolate together and let cool slightly.

Whisk the eggs and sugar

• In a large bowl, whisk the eggs and caster sugar until pale and fluffy.

Combine the batter

• Add the chocolate and butter mixture to the eggs and sugar and whisk to combine.
• Sift in the flour, cocoa powder and salt, then fold until just incorporated.

Bake the brownie base

• Pour the batter into the lined tin and spread evenly.
• Bake for 22 minutes, then let it cool completely in the tin.

Brew the coffee

• Brew the strong coffee and allow it to cool.

Layer the ladyfingers

• Briefly dip each ladyfinger into the coffee.
• Arrange them tightly in a single layer over the cooled brownie base.

Make the mascarpone cream

• Whip the double cream to soft peaks.
• Add the sugar and mascarpone, then beat until thick and smooth.

Assemble and chill

• Spread the mascarpone cream evenly over the ladyfinger layer.
• Cover the tin with foil or cling film and refrigerate overnight, at least 8 hours.

Decorate and serve

• Just before serving, dust the top with unsweetened cocoa powder.