Beat the curd and mascarpone in a mixing bowl with the whisks of the hand mixer for 1-2 minutes. Separate the eggs. Stir egg yolks and sugar into the cream. Beat egg whites with vanilla sugar until stiff and fold into the cream. Put them in a cold place.
Wash the grapes, rub dry and cut in half. Crumble the biscuits. Divide 3/4 of the biscuits between 4 glasses (each containing approx. 250 ml). Put half of the cream on top. Spread 3/4 of the grapes on the cream.
Spread the rest of the cream on the grapes. Decorate with remaining grapes and crumbled biscuits.