Tomato-Onion-Cheese Casserole
["4 c. (1 lb.) thinly sliced onion", "4 medium-size ripe tomatoes (2 lb.), peeled and sliced", "1 tsp. salt", "1/4 tsp. pepper", "1/2 tsp. dried basil leaves", "6 slices processed American cheese, cut in half", "1/2 c. packaged bread crumbs", "3 Tbsp. butter or margarine, melted"]
["Preheat oven to 350\u00b0.", "Lightly grease a 1 1/2-quart casserole dish."]
["onion", "tomatoes", "salt", "pepper", "basil", "American cheese", "bread crumbs", "butter"]