Sprinkle roast on all sides with 1/2 teaspoon salt and 1/8 teaspoon pepper, place roast, bone ends up, in a shallow roasting pan.
Cook sausage in a skillet until browned, stirring to crumble, drain well.
Combine sausage and next 7 ingredients, stir to moisten bread.
Fill center of roast with sausage mixture, cover with aluminum foil.
Punch a hole in foil, insert meat thermometer into roast, making sure it does not touch foil, bone, or fat.
Bake at 325Â° for 3 to 3 1/2 hours or until meat thermometer registers 160Â°.
Garnish with apple wedges and watercress, if desired.