Step 1Beat egg yolks with powdered sugar on medium speed until pale and creamy, about 5 minutes. Add mascarpone and beat until thick and firm.
Step 2Whip egg whites until fluffy and firm, 3 to 4 minutes. Fold egg whites into mascarpone mixture.
Step 3Combine espresso and Amaretto. Quickly dip half ladyfingers in espresso mixture on each side. Layer ladyfingers in bottom of an 9-inch square glass baking dish. Spread ladyfinger layer with half mascarpone mixture. Dip remaining ladyfingers in espresso mixture, layer in dish, then spread remaining mascarpone on top. Chill 2 hours.