Heat oven to 375°. Prepare Herbed Bread Stuffing. Stuff chicken just before roasting—not ahead of time. Fill wishbone area with some of the stuffing. Fasten neck skin to back with skewer. Fold wings across back with tips touching. Fill body cavity lightly with remaining stuffing. (Do not pack—stuffing will expand while cooking.) Tie or skewer drumsticks to tail.
Place chicken, breast side up, on rack in shallow roasting pan. Brush with margarine. Do not add water. Do not cover. Roast 2 to 2 1/2 hours or until drumstick moves easily when lifted or twisted.
Herbed Bread Stuffing:
Cook celery and onion in margarine in 10-inch skillet, stirring occasionally, until onion is tender. Stir in about 1 cup of the bread cubes. Turn into deep bowl. Add remaining ingredients; toss. Stuff chicken just before roasting.
Place chicken on warm platter; keep warm while preparing gravy. Pour drippings from roasting pan into bowl, leaving brown particles in pan. Return 2 tablespoons drippings to pan. (Measure accurately because too little fat will make gravy lumpy.)
Stir flour into drippings in pan. (Measure accurately so gravy will not be greasy.) Cook over low heat, stirring constantly, until mixture is smooth and bubbly; remove from heat. Stir in broth. Heat to boiling, stirring constantly. Boil and stir 1 minute. Stir in a few drops browning sauce if desired. If thinner gravy is desired, stir in additional broth or other liquid. Sprinkle with salt and pepper.