-
Beat together yolks and 2 Tbsp sugar in a large bowl with an electric mixer at medium speed until thick and pale, about 2 minutes. Beat in mascarpone until just combined.
-
Beat whites with salt in another large bowl with cleaned beaters until they just hold soft peaks. Add remaining 3 Tbsp sugar, a little at a time, beating, then continue to beat until whites just hold stiff peaks.
-
Beat cream in another bowl with cleaned beaters until it just holds stiff peaks. Gently but thoroughly fold cream into mascarpone mixture, then fold mixture into whites.
-
Pour espresso into a shallow bowl. Dip half of amaretti (15 to 20) in espresso for about 20 seconds, turning to coat both sides and letting excess drip off. Arrange in 1 layer in an 8-inch square baking dish. Spread half of mascarpone mixture evenly over amaretti. Make another layer in same manner with remaining amaretti (dipped in espresso) and mascarpone mixture. Chill at least 6 hours.