Place chicken breasts in a glass casserole baking dish. In a mixing bowl, combine soup mix, cranberry sauce, and dressing. Pour over the chicken breasts. Cover with plastic wrap and marinate for at least 8 hours in the refrigerator; 2 to 3 hours at room temperature. Cover casserole dish loosely with foil. Bake at 350 degrees F (175 degrees C) for 1 hour and 15 minutes, or until done.