When beating the egg whites, the bowl must be clean and dry in order for the eggs to expand properly. Also, the proteins will expand better at warmer temperatures, so let the eggs rest to room temperature before beating.
Coffee dipping sauceBeat egg yolks and sugar in another bowl for 3 minutes until thick and pale. Add mascarpone and mix until just combined. Beat the cream in a separate bowl until soft peaks form, then fold into mascarpone mixture.
1 1/2 C really really strong black coffee/espresso cooled
2 Tbsp kahlua (will be sweeter) or rum although either one is optional
16 (I always like more) large lady fingers
2 eggs, separated
8 oz mascarpone
1 C heavy whipping cream
2 Tbsp cocoa powder
Place the egg whites in another different, small, clean, dry bowl and beat with electric beaters until soft peaks form, fold quickly into the cream mixture.
Combine coffee and liquor in a different shallow bowl. Dip half the biscuits into the coffee, arrange in the base of a serving dish or bowl. Spread 1/2 cream mixture, then repeat biscuits. Spread remaining cream then liberally dust with cocoa powder.
Refrigerate overnight or at least 2 hours.