Brew strong coffee or espresso and let it cool.
In a mixing bowl, beat egg yolks and sugar until thick and pale.
Add mascarpone cheese and beat until smooth.
In another bowl, beat egg whites until stiff peaks form.
Gently fold the egg whites into the mascarpone mixture.
Quickly dip ladyfingers into the cooled coffee and arrange them in a single layer in the bottom of a dish.
Spread half of the mascarpone mixture over the ladyfingers.
Repeat layers with remaining ladyfingers and mascarpone mixture.
Cover and refrigerate for at least 4 hours or overnight.
Before serving, dust with cocoa powder.