How to Make It
In a food processor, combine the butter, 6 tablespoons of the maple syrup, 3 tablespoons of the lemon juice, the lemon zest, coarsely ground pepper, and salt. Process until blended and transfer to a bowl. In another bowl, combine the remaining 1/4 cup maple syrup, 1 tablespoon lemon juice, and the finely ground pepper.
In a sturdy 2-gallon plastic bag, combine the lemon juice, maple syrup, corn oil, shallots, garlic, thyme, bay leaves, lemon zest, and pepper. Add the turkey to the bag, squeeze out as much air as possible and seal the bag. Distribute the marinade evenly over and inside the turkey. Set the turkey, breast side down, in a bowl in the refrigerator and marinate for 24 hours, turning occasionally.
Preheat the oven to 450°. Position the oven rack near the bottom of the oven. Wipe off the shallots and garlic from the turkey and pat dry. Strain the marinade into a bowl, skim off the oil, and reserve. Set the herbs, garlic, and shallots aside separately.
Using your fingers, carefully loosen the turkey skin over the breast and thighs. Put all but 3 tablespoons of the softened maple-pepper butter in a pastry bag fitted with a small round tube and pipe it under the breast and thigh skin, patting gently to spread the butter. Alternatively, spread it evenly with your fingers.
Put one-third each of the diced onions and celery in the cavity. Tie the legs together with kitchen string and set the turkey, breast side up, on a rack in a large roasting pan. Rub the breast and thigh skin with the remaining maple butter and roast for 30 minutes, basting twice. The skin may appear dark in patches because the maple syrup in the marinade and the butter caramelize as the turkey cooks; cover it loosely with foil to keep the skin from burning.
Lower the oven temperature to 350°. Spread the remaining onions and celery around the turkey and roast for about 1 1/2 hours longer, or until an instant-read thermometer inserted in the thickest part of the breast just above the wing joint reaches 165° and the juices run clear. During the last 30 minutes, add the reserved shallots, garlic, and herbs to the pan, remove the foil from the turkey and brush twice with the maple-pepper glaze. Transfer to a carving board and let stand, loosely covered with foil, for 30 minutes.
Remove the whole legs from the turkey, cutting them off at the hip joint. Cut off the wings from the breast. Return the legs and wings to the pan and roast for about 30 minutes longer, until an instant-read thermometer inserted in the thickest part of the thigh reaches 180° and the juices run clear. Transfer the legs and wings to the turkey on the carving board, cover with foil and let stand for 15 minutes before carving.
Set the roasting pan over 2 burners over high heat and cook the vegetables, stirring, until golden brown. Carefully pour off all but 2 tablespoons of the fat. Add the flour and whisk for 1 minute. Add the reserved marinade and the chicken stock and bring to a boil, scraping up any browned bits. Simmer, whisking constantly, for 3 minutes. Strain the gravy into a saucepan and boil over high heat until reduced by half, about 10 minutes. Season with salt and pepper, pour into a sauceboat and serve alongside the turkey.
For more great Thanksgiving recipes, menus and pairings, go to our Thanksgiving Recipes page.