Pre-heat oven to 325 degrees. In a large bowl, combine the melted butter and stuffing mix, and mix well. Set aside.
Spray a 2-quart casserole dish with a non-stick spray. Place the chicken breasts in the casserole dish. Top with undiluted soup. Place cheese slices evenly over the soup. Top with stuffing/butter mixture. Cover with aluminum foil and bake for 1 hour, removing the aluminum foil half-way through.