1 (12-pound) turkey
Warm Farmhouse Herbed Stuffing
Approximately 8 cups warm Homemade Turkey Stock
4 tablespoons (1/2 stick) unsalted butter, softened, plus additional, melted, if needed for gravy
1 3/4 teaspoons salt
6 tablespoons all-purpose flour
Special equipment: small metal skewer; kitchen string; aluminum foil; large flameproof roasting pan with flat or V-shaped rack; bulb baster (optional); instant-read thermometer; 2-quart glass measuring cup; gravy separator (optional)

Place oven rack in lowest position and preheat oven to 325°F. Butter 8-inch square baking dish or 2-quart casserole. Lightly brush roasting rack with vegetable oil and place in roasting pan.

Remove plastic or paper packet of giblets from turkey (usually in small cavity). Remove from packaging and rinse; reserve gizzard and heart; discard floppy, dark purple liver. Remove neck from large cavity. Remove from packaging, rinse, and reserve. Using tweezers or needlenose pliers, remove any feathers and quills still attached to skin (kosher turkeys tend to require this more than others). Pull off and reserve any visible pale yellow knobs of fat from either side of tail (not found on all birds).

Rinse turkey inside and out with cold water and pat dry. Loosely fill small (neck) cavity with stuffing. Fold neck skin under body and fasten with metal skewer. Loosely fill large body cavity with stuffing. Transfer remaining stuffing to buttered dish and drizzle with 1/4 cup stock. Cover with aluminum foil and refrigerate until ready to bake.

Transfer turkey, breast-side up, to rack in roasting pan. Tuck wing tips under breast and tie drumsticks loosely together with kitchen string. Rub turkey all over with softened butter and sprinkle with 1 teaspoon salt and 1/2 teaspoon pepper. Tightly cover breast area with foil, leaving wings, thighs, and drumsticks exposed.

Transfer gizzard, heart, neck, and reserved turkey fat to roasting pan around rack. Pour 2 cups stock into pan.

Roast turkey 45 minutes. Baste with pan juices (lift up foil to reach breast area) and continue roasting, basting every 45 minutes, 1 1/2 hours more (2 1/4 hours total). Baste again and, if pan juices have evaporated into glaze, add 1 cup stock to pan. Roast another 45 minutes (3 hours total). Remove foil from breast area, baste, and add stock if necessary, until instant-read thermometer inserted into fleshy part of thigh (close to but not touching bone) registers 180°F, about 1 hour more (4 hours total).

Insert instant-read thermometer into center of stuffing in body cavity. If thermometer does not read 165°F, transfer stuffing to microwave-safe baking dish and microwave on high until 165°F, about 3 minutes for 10 degrees. Cover and keep warm. Using turkey holders (or by inserting large metal serving spoon into body cavity), transfer turkey to large serving platter. Let stand 30 minutes before carving.

Meanwhile, bake extra stuffing and make gravy: Raise oven temperature to 350°F. Remove giblets and neck from roasting pan and discard. Pour pan juices into measuring cup or gravy separator. Let stand until fat rises to top, 1 to 2 minutes, then skim off and reserve fat or, if using separator, carefully pour juices into measuring cup, reserving fat left in separator.

Transfer foil-covered dish of extra stuffing to oven and bake 10 minutes. Meanwhile, add enough remaining stock to pan juices to total 4 cups. Measure turkey fat, adding melted butter if necessary to total 6 tablespoons. Straddle roasting pan across 2 burners on moderate heat and add fat. Whisk in flour, scraping up browned bits on bottom of pan, then cook, whisking constantly, 1 minute. Whisk in pan juice–stock mixture and bring to a boil, whisking often. Reduce heat to moderately low and simmer, whisking occasionally, until gravy thickens, about 5 minutes. Whisk in remaining 3/4 teaspoon salt and 1/2 teaspoon pepper and keep warm. (Gravy can be kept warm over very low heat, covered, up to 20 minutes. If it thickens, thin with additional stock before serving. If skin forms on top, whisk well to dissolve.)

When extra stuffing has baked 10 minutes, remove foil and bake, uncovered, until heated through, about 10 minutes. Pour gravy through fine-mesh sieve into large bowl, then transfer to gravy boat. Carve turkey and serve gravy and stuffing alongside.