Preheat oven to 425 degrees. In a small saucepan, combine the chestnuts with water to cover. Bring to a boil and boil for 20 minutes. Drain well. Have your butcher butterfly the raw turkey breast to a consistent 1/2-inch thickness. In a mixing bowl, stir together the chestnuts, pear cubes, rosemary leaves, bread crumbs, and eggs and mix well. Season the surface of the turkey breast with salt and pepper and lay the stuffing mix on top. Roll the breast and stuffing up like a jelly roll and tie with butcher's twine. Place in a roasting pan and roast for 60 to 75 minutes, until an instant-read thermometer reads to 155F at the center. Remove from the oven and allow to rest 10 minutes before carving.
Recipe courtesy Mario Batali, "Simple Italian Food: Recipes from My Two Village"