Preheat oven to 350 degrees. Lightly grease a 9x13 baking dish. Arrange chicken breasts in the baking dish. Place one slice of swiss cheese on top of each chicken breast. Combine soup and millk in a medium bolw, then pour over the top of the chicken breasts. Sprinkle with stuffing mix. Pour melted butter over top. Cover with foil, then bake 50 minutes, or until chicken is no longer pink and juices run clear.