Prepare Stuffing Mix According To Package Directions; Set Aside. Place The Chicken In A Greased 13-In. X 9-In. X 2-In. Baking Dish. Combine The Soup, Milk, Celery, Onion, Salt And Pepper Until Blended; Pour Over Chicken. Top With Stuffing. Bake, Uncovered, At 350 Degrees F For 30-35 Minutes Or Until Bubbly.