With a food processor, coarsely pulse and chop the cranberries. Do not grind them too fine; leave in larger chunks (see photo).

In a small bowl, mix together the cranberries and sugar and chill in the refrigerator overnight.

Toast the walnuts either in microwave (2 minutes), or oven. Chop and set aside.

Whip 2 cups whipping cream; add the powdered sugar and vanilla. The whipping cream should be really stiff.

In a large bowl, add the cranberry mixture, walnuts, chopped grapes. Fold the thick whipping cream into the cranberry mixture. Gently toss; chill the salad until ready to serve.

Leftovers can be frozen and served as a frozen salad later.