Marinate the chicken in the ranch dressing overnight (or for at least 4 hours).
Preheat the oven to 450 degrees F (230 degrees C).
Combine the bread crumbs, Parmesan cheese, black pepper, sage and salt and mix well. Coat the marinated breasts in the breading mixture and place in a 9x13 inch baking dish. Bake in the preheated oven for 20 minutes, then REDUCE HEAT to 350 degrees F (175 degrees C) and bake for 30 minutes or until done and juices run clear.