Preheat oven to 180°C

Remove giblets and neck from Turkey; discard. Rinse turkey thoroughly with cold water; pat dry. Starting at neck cavity, loosen skin from breast and drumsticks by inserting fingers, gently pushing between skin and meat. Combine sage, 2 teaspoons chives, 1 teaspoon thyme, and 1 teaspoon parsley in a small bowl. Rub sage mixture under loosened skin and inside body cavity. Tie ends of legs with cord. Lift wing tips up and over back; tuck under bird.

Place turkey on a broiler pan coated with cooking spray or on a rack set in a shallow roasting pan. Insert meat thermometer into meaty part of thigh, making sure not to touch bone. Bake at 180° for 3 hours or until thermometer registers 85°C. (Cover turkey loosely with foil if it gets too brown.) Remove turkey from oven. Cover loosely with foil; let stand at least 10 minutes before carving.

Place a zip-top plastic bag inside a 2-cup glass measure. Pour drippings from pan into bag; let stand 10 minutes (fat will rise to the top). Seal bag; snip off 1 bottom corner of bag. Drain drippings into a medium saucepan, stopping before the fat layer reaches the opening. Stir in 2 1/2 cups broth and sherry. Bring to a boil; reduce heat, and simmer 10 minutes. Combine 1/4 cup broth and flour in a small bowl, stirring well with a whisk. Stir into sherry mixture, and bring to a boil, stirring constantly. Stir in 2 tablespoons parsley, 1 teaspoon chives, and 1 teaspoon thyme. Serve sauce with turkey.