Cook and drain 4 Cups cubed, pared butternut or hubbard squash. Meanwhile, cook 1 medium onion, sliced, in 2 tbls. butter till tender, but not browned. approximately 20 minutes. Remove from heat, add 1 cup sour cream and 1/2 tsp. salt., stir well. Place hot cooked squash on platter, sprinkle with pepper, pour sauce over. Sprinkle with 1/2 teaspoon basil.