1.Brew the Espresso and allow it to cool. Combine the cooled Espresso with the coffee liqueur in a shallow dish.
2.Whisk the egg yolks and half the sugar in a large bowl until pale and creamy. Add the mascarpone and beat until smooth.
3.In a separate bowl, beat the egg whites with the remaining sugar until stiff peaks form.
4.Wash the heavy cream and vanilla extract in another bowl until soft peaks form, then gently fold it into the mascarpone mixture.
5.Fold the beaten egg whites into the mascarpone mixture in two batches until fully incorporated.
6.Quickly dip each ladyfinger into the coffee mixture and layer them at the bottom of a dish.
7.Spread half of the mascarpone mixture over the ladyfinger layer. Repeat with another layer of dipped ladyfingers and the remaining mascarpone mixture.
8.Refrigerate for at least 4 hours or overnight.
9.Before serving, dust the top with cocoa powder.