For an even deeper flavor, consider adding a few cloves of garlic to the chicken cavity along with the lemon, rosemary, and onion. If the chicken skin starts to brown too quickly, tent it loosely with foil during the last 30 minutes of roasting. The pan drippings make an excellent base for a flavorful gravy. Simply strain the drippings, skim off the excess fat, and thicken with a cornstarch slurry. Feel free to add other herbs like thyme or sage to complement the rosemary and lemon flavors.