Spray a 1-1/2-quart baking dish w/ cooking spray. Heat oven to 350. Cook egg[plant in salted boiling water 10 min, drain. In lg bowl, mix eggplant, soup, mayonnaise, Egg Beaters, onion and cheese until combined. Place mix in baking dish. In another bowl, mix together Ritz cracker crumbs and butter. Sprinkle evenly over casserole. Bake 25 min, or until cheese is melted and casserole top is browned.