Wash the grapes and cut them in half. Whip the cream until stiff and fold into the quark.
Put the biscuits in a freezer bag and roll over them with a rolling pin so that the biscuits crumble. Put the crumbled biscuits in a bowl, then pour the quark over it and finally spread the grapes on top.
Let it steep in the refrigerator for at least 30 minutes.