Cook eggplant in boiling salted water 6-8 minutes or until tender; drain well. Combine eggplant, milk, soup, egg, onion, 3/4 cup stuffing mix, and salt, stirring well. Spoon into a lightly greased 1 quart casserole. Combine remaining 1/2 cup stuffing mix and butter; sprinkle over eggplant mixture. Bake at 350 degrees for 20-25 minutes.