There are two ways to thaw a frozen bird. The easiest: Place it on a tray in the refrigerator for three days. The quickest: Submerge the wrapped turkey, breast side down, in cold water for 5 to 6 hours; change the water every half hour to keep it cold.
Remove giblets and neck from turkey and reserve for Classic Pan Gravy. Rinse turkey with cold water, and pat dry. Trim excess fat. Starting at neck cavity, loosen skin from breast and drumsticks by inserting fingers, gently pushing between the skin and meat. Combine the mustard, sage, black pepper, and garlic. Rub the mustard mixture under loosened skin. Lift the wing tips up and over back; tuck under turkey.
Place turkey, breast side up, in a shallow roasting pan. Pour broth over turkey. Insert a meat thermometer into meaty part of thigh, making sure not to touch the bone. Place turkey in a 450° oven; immediately reduce the oven temperature to 325° (do not remove turkey from oven). Bake for 2 hours or until thermometer registers 180°, basting turkey frequently with pan juices. Reserve 3 tablespoons drippings for Classic Pan Gravy; let turkey stand for 25 minutes. Discard skin. Serve with Classic Pan Gravy.