Crumble all but four pieces of amaretti. Wash the grapes and pluck them from the stems. Leave whole or cut in half as desired. Beat the egg whites until stiff, add 1 tablespoon of sugar little by little.
Mix mascarpone, quark, milk, remaining sugar, vanillin sugar and lemon peel to a creamy mixture. Fold in the beaten egg white. Layer Amaretti crumbs (up to 1 tablespoon) and grapes alternately with the mascarpone cream in 4 glasses. Serve decorated with whole amaretti and amaretti crumbs