Acorn squash is a good source of fiber, potassium, and vitamins A and C. Plus it's fast and easy to prepare. In a small bowl, toss apple slices (from a peeled and cored apple) with 2 tablespoons brown sugar. Set aside. Pierce a small acorn squash several times with a knife. Microwave squash on high until tender, about 5 minutes. Then cut in half. Scrape out seeds and discard. Fill with apple slices. Return to microwave and cook until apples are soft, about 2 minutes. Top each half with 1 teaspoon margarine.