Chop the cranberries: Add the fresh cranberries to a food processor and pulse until finely chopped. It's okay to leave some whole berries for extra texture.

Add the sugar: Transfer the chopped cranberries to a large mixing bowl. Add the granulated sugar and stir until combined. Let the mixture sit for 1 hour.

Add the remaining ingredients: Add the crushed pineapple, Cool Whip, and miniature marshmallows to the cranberry mixture.

Fold and serve: Gently fold everything together until well combined. Transfer to your favorite serving bowl and add extra cranberries on top if desired. Keep chilled until ready to serve.