- Place the pancetta in a large skillet set over medium, medium-high heat. Cook pancetta almost crispy, about 5 minutes. Mix in the apple, onion and celery and cook 5 minutes more, or until tender. Remove pan from the heat.
- Cut the bread into 1/2-inch cubes and place in a large bowl. Spoon the apple mixture over the bread. Add the apple juice, lemon juice, sage, salt and pepper and toss to combine.
- Remove the neck and innards from the main cavity of the turkey. Place the neck in the roasting pan; discard innards unless you wish to prepare them separately.
- Fill the main cavity of the turkey with some of the stuffing, making sure it’s loosely stuffed, not tightly packed in. (If you pack it in, it won’t get hot enough to kill any bacteria present in the turkey.) Also stuff the cavity behind the large flap of skin at the neck end of the bird. (You can pack the dressing tighter here, as it’s closer to the heat.) Any leftover stuffing can be baked in a lightly buttered or oiled casserole dish (see Note).
- Preheat oven to 325°F. Tie the legs of the turkey together; fold and tuck wings under the body. Brush the bird with olive oil, and then season with salt and pepper. Roast turkey, uncovered, 1 1/2 hours. Baste turkey with pan juices, and then give the pan a 180-degree turn. Roast turkey another 1 hour and 15 minutes.
- Insert an instant-read meat thermometer deep into an inner thigh of the turkey, not touching the bone. If it registers 180°F (82°C), the turkey is ready. If it doesn’t, baste the bird again and roast 15 to 30 minutes more, or until the 180°F (82°C) temperature is achieved.
- Transfer turkey to a large platter. Remove stuffing and set in a heatproof dish. If stuffing does not feel hot, bake stuffing a few minutes longer, until the centre registers a bacteria-killing 165˚F (74˚C) or higher on an instant-read thermometer. Tent turkey with foil and rest the bird until you’re ready to carve, at least 15 minutes.
- To make gravy, skim excess fat from the pan drippings. Place the pan on the stovetop over medium-high heat. Add 3 cups of the stock and bring to a boil. Place the flour and the remaining stock in a bowl and whisk until smooth. Whisk the mixture into the pan and simmer until thickened gravy forms, about 5 minutes. Carve the turkey and serve the stuffing and gravy in a sauceboat alongside.
Note: To bake any stuffing that did fit in the bird, after placing in a buttered or oiled casserole dish, when the turkey is cooked and resting, set the dish of stuffing in the oven. Bake 20 minutes. Uncover and bake 10 minutes more, or until the dressing is hot and crisp and golden on top.