Zucchini Casserole
["1 med onion, sliced in rings", "4 med zucchini, sliced", "2 tomatoes, sliced", "salt and pepper to taste", "1/2 cup Parmesan cheese, grated", "2 Tbsp butter (if desired)"]
["Cook onions in microwave 3 minutes until soft, but not done.", "Spray large casserole dish with Pam.", "Place zucchini in bottom of dish. Cover with onions.", "Add tomato slices and season to taste.", "Top with cheese.", "Cover and bake at 350\u00b0 for 15 minutes.", "Uncover and continue baking until zucchini reaches desired tenderness."]
["onion", "zucchini", "tomatoes", "salt", "Parmesan cheese", "butter"]