Finely chop the cranberries in a food processor, pulsing carefully so they remain finely chopped rather than turning into a purée. Transfer them to a bowl and stir in the granulated sugar.

Cover the cranberry mixture and refrigerate it overnight. This resting period softens the berries and gives the sugar time to dissolve.

Stir the undrained crushed pineapple, miniature marshmallows, and chopped walnuts or pecans into the chilled cranberry mixture.

In a separate bowl, beat the heavy whipping cream with the confectioners' sugar until stiff peaks form. Watch closely near the end so the cream stays smooth and does not become grainy.

Gently fold the whipped cream into the cranberry mixture until the color is mostly even and the salad remains light and fluffy. Cover and refrigerate until thoroughly chilled before serving.