If using fresh cranberries, rinse them thoroughly. If using frozen, ensure they are thawed. In a food processor, pulse the cranberries with the granulated sugar until finely chopped but not pureed. Alternatively, finely chop the cranberries by hand with a sharp knife and mix with sugar. Set aside.

Open the can of crushed pineapple and drain it very well, pressing out as much liquid as possible. You can use a fine-mesh sieve or colander for this. Excess liquid will make the salad watery.

In a large mixing bowl, combine the chopped cranberry mixture, the well-drained crushed pineapple, and the miniature marshmallows. Stir gently to combine evenly.

Add the thawed whipped topping to the cranberry mixture. Gently fold it in with a rubber spatula until just combined and no streaks of whipped topping remain. If desired, gently fold in the chopped pecans or walnuts for added texture.

Cover the bowl with plastic wrap and refrigerate for at least 2-4 hours, or preferably overnight, to allow the flavors to meld and the salad to set. Serve chilled.