Halve squash; remove seeds. Place squash, cut sides down, in a shallow baking dish. Bake in a 350 degree F. oven for 30 minutes. Meanwhile, in a large skillet cook turkey or chicken, mushrooms, sweet pepper, and garlic until turkey or chicken is brown and vegetables are tender; drain well. Stir in shredded cheese and cream cheese. Turn squash cut side up. Spoon turkey mixture into squash. Bake, covered, about 20 minutes more or until squash is tender. Stir together bread crumbs and melted margarine or butter; sprinkle over turkey filling. Bake, uncovered, for 3 minutes more. Makes 4 servings.