Have butcher prepare turkey as follows:
Remove wings and separate tips from wings. Remove legs and thighs. Separate legs from thighs. Bone breast but keep breast and skin intact. Breast will weigh about 7 1/2 pounds. Keep turkey carcass.
To prepare turkey stock:
Place carcass in large heavy pot. Add giblets (except liver) and wing tips. Add cold water to cover carcass. Add 1/2 teaspoon whole black peppercorns, a head of unpeeled garlic, cut in half horizontally, and 6 sprigs of sage. Bring to a boil, skimming any foam from top. Lower heat to medium and cook for 2 hours. Discard carcass and giblets. Strain broth through a fine-mesh sieve, pressing softened garlic through the sieve. Place strained broth in large clean pot. Add 1 teaspoon salt, and bring to a boil. Lower heat and simmer until broth is reduced to 6 cups. Set aside.
Meanwhile, preheat oven to 325 degrees and prepare ballottine:
Remove skin from turkey thighs and cut meat into 1/4- to 1/2-inch cubes. You will have about 4 cups. Place in a bowl. Finely chop enough sage to get 1/2-cup (packed). Add to turkey. Push 4 cloves of garlic through a garlic press and add to turkey with 1 teaspoon salt and freshly ground black pepper. Mix well.
Lay boned breast flat, flesh-side up, on a clean flat surface. Position breast so there is a lobe to your left and a lobe to your right. Butterfly breast so that it lies flat. Sprinkle lightly with salt and freshly ground black pepper. Place turkey mixture across lobes in a long sausage shape in center of breast. You want the mixture to go from end to end. Roll up tightly like a jellyroll. Tie string tightly around rolled breast at 1-inch intervals.
You will have a ballottine that is about 16 inches long. Also tie string around the length of the breast. Place ballottine in large shallow roasting pan. Add 1/2 cup stock to bottom of pan. Bake for 50 minutes. Baste with pan juices. Place wings and legs in pan. Add 1/2 cup stock. Continue to bake 50 to 55 minutes or until thermometer reads 140 to 145 degrees.
Remove pan from oven. Breast will continue to cook. Transfer ballottine, wings and legs to large platter and let rest. Add 5 cups stock to roasting pan, scraping up all browned bits. Strain through a sieve into clean pot. Add 1 small clove garlic pushed through a garlic press, salt and pepper to taste. Cook over high heat until reduced to 3 cups.
Remove strings from turkey. Cut ballottine into thin slices and serve with wings, legs and hot garlic "jus." Garnish with sprigs of fresh sage.
Makes 12 servings.