This is an easy and yummy casserole to take to your next potluck!
1 red onion, sliced
1 green pepper, cut in thin strips
4 medium zucchini, sliced & unpeeled
1, 16 oz. can diced tomatoes, undrained
1 teaspoon salt
1/2 teaspoon pepper
1/2 teaspoon basil
1 tablespoon margarine
1/4 cup grated Parmesan cheese
Combine all the ingredients, excluding the cheese and margarine, in a slow cooker. Cook on a low setting for 3 hours. Add the margarine and sprinkle the cheese on top. Cook for another 1 1/2 hours on the low setting.