Drain pineapple well. Mix pineapple with cherry pie filling and sweetened condensed milk. Fold in the nuts, sour cream, and Cool Whip.
Transfer to a serving dish, cover, and refrigerate until ready to serve.
Notes
Make it ahead: cover and refrigerate the salad after making it. Refrigerate for up to 24 hours before serving. Freezing: I don't recommend freezing the salad—it will negatively affect the texture. Garnish: reserve a few chopped pecans and a few cherries from the pie filling (rinse and drain them) for the top. Variations: add 2 cups of mini marshmallows, 1 cup of fresh blueberries, 1 cup of shredded coconut, or 1 (drained) can of mandarin oranges. Substitutions: replace the pecans with walnuts, substitute 2 cups of heavy cream (whipped) for the whipped topping, use pineapple chunks instead of crushed pineapple.