Step 1 of 9
Whisk egg yolks and sugar over double boiler until thick and pale.
Step 2 of 9
Remove from heat and whisk in mascarpone until smooth. Let cool.
Step 3 of 9
Whip heavy cream to stiff peaks. Fold into mascarpone mixture.
Step 4 of 9
Combine espresso and coffee liqueur in a shallow dish.
Step 5 of 9
Quickly dip ladyfingers in espresso mixture and arrange in a 9x13 dish.
Step 6 of 9
Spread half the mascarpone cream over ladyfingers.
Step 7 of 9
Repeat with another layer of dipped ladyfingers and remaining cream.
Step 8 of 9
Cover and refrigerate for at least 4 hours or overnight.
Step 9 of 9
Dust generously with cocoa powder before serving.