Whisk the strained yoghurt with half the sugar. Put half the biscotti in a tray and smear the mixture over them.
Arrange the fruits on top and place another layer of biscotti and yoghurt cream. Once the cake is prepared, put it in the fridge to cool.
Meanwhile, whip the egg whites into snow with the remaining sugar. Garnish the cake with the egg whites and leave it in the refrigerator for about 1 hour.