Nutrition per serving may change if servings are adjusted.
6 tablespoons unsalted butter, softened
6 cloves garlic, minced
1 shallot, minced
1½ tablespoons chopped fresh rosemary plus 5 sprigs, divided
1½ tablespoons whole-grain mustard
1½ teaspoons grated lemon zest
1 teaspoon salt
1 (12 pound) turkey
1 small onion, quartered
1 lemon, halved
1 stalk celery, cut into 4 pieces
1 carrot, cut into 4 pieces
5 sprigs fresh sage
5 sprigs fresh thyme
¼ cup pan drippings from turkey
1 shallot, minced
2 cloves garlic, minced
¼ cup all-purpose flour
½ cup dry white wine
3 cups low-sodium chicken broth
1 tablespoon chopped fresh sage
1 tablespoon chopped fresh thyme
½ teaspoon salt
¼ cup heavy cream
1 teaspoon coarsely ground black pepper
To prepare turkey: Combine butter, 6 minced garlic cloves, shallot, chopped rosemary, mustard, lemon zest, and 1 tsp. salt in a small bowl.
Remove giblets and neck from turkey; reserve for another use or discard. Pat the outside and cavity of the turkey very dry with paper towels. Place on a large rimmed baking sheet.
Starting at the neck cavity, insert two fingers between skin and meat, gently loosening the skin along the breast. Push gently until most of the skin is loosened. Repeat on the other side with the thighs and drumsticks. Rub the butter mixture under the loosened skin, massaging it into the breast and legs. Refrigerate the turkey, uncovered, for 4 hours.
Remove the turkey from the refrigerator and let stand at room temperature for 1 hour.
Preheat oven to 450°F.
Place the turkey, breast-side up, on the rack of a large roasting pan. Stuff the cavity with onion, lemon, celery, carrot, rosemary sprigs, sage sprigs, and thyme sprigs. Lift the wing tips up and over the back; tuck under the turkey. Secure the legs with kitchen string.
Roast the turkey, uncovered, for 30 minutes. Reduce oven temperature to 350°F. Cover the turkey loosely with Reynolds Wrap foil and roast until a thermometer inserted into the thickest part of the breast and innermost part of the thigh reaches 165°F, 1¾ to 2 hours (see Tips). Carefully transfer the turkey to a carving board. Reserve ¼ cup of the pan drippings for making the gravy (discard the remainder). Let the turkey stand for 30 to 45 minutes before carving.
Meanwhile, to prepare gravy: Heat the drippings in a large skillet over medium-high heat. Add shallot and garlic; cook, stirring, until tender, about 3 minutes. Whisk in flour and cook until it turns golden and the mixture begins to look like a brown, crumbly paste (almost like crumbled cooked sausage), 1 to 2 minutes. Whisk in wine; cook until almost evaporated, about 1 minute. Whisk in broth, sage, thyme, and salt; cook, whisking occasionally, until thickened, 10 to 14 minutes.
Strain the gravy through a sieve into a medium bowl. Discard the solids. Wipe the pan clean and return the gravy to it. Add cream and peppercorns; cook over low heat until heated through, 2 to 3 minutes.
Carve the turkey and serve with the gravy.
Tips: If the turkey is browning unevenly, rotate it halfway through cooking.
When roasting a turkey, the only reliable way to check for doneness is to use an instant-read thermometer in both the breast and the thigh. Instant-read thermometers are available at kitchenware stores, online, and often in supermarkets at the meat counter for as little as $10a worthwhile investment.