Place the chicken in a greased 13-in. x 9-in. x 2-in. baking dish. Sprinkle with minced onion, salt, garlic powder and pepper. Top each with a slice of cheese.
In a large bowl, combine the soup, sour cream and water; pour over chicken. Toss the cracker crumbs and butter; sprinkle over chicken. Bake, uncovered, at 350° for 30-40 minutes or until chicken juices run clear and crumbs are golden.