1. Prepare the Sage Butter:

In a small bowl, mix the softened butter with chopped sage, thyme, rosemary, minced garlic, lemon zest, salt, and pepper. This sage butter will be used to rub all over the turkey.

2. Prepare the Turkey:

1. Preheat your oven to 250°F 
2. Pat the turkey dry with paper towels.
3. Loosen the skin of the turkey (starting from the neck and carefully working your way down), being careful not to tear it. Rub half of the sage butter directly under the skin, spreading it evenly over the breast meat.
4. Rub the remaining sage butter over the outside of the turkey.
5. Season the turkey generously with salt and pepper, both inside the cavity and on the skin.
6. Stuff the turkey cavity with the lemon quarters, onion, and halved garlic head.

3. Roast the Turkey:

If using a roasting bag: 

1. Open the bag, add 1 tablespoon of flour and shake it all around to roughly coat the inside. This step is important: the flour will combine with the fat and juices from the turkey ensuring the bag won’t burst.
2. Fill the bag with cut vegetables (onion, carrot, celery) and stems of fresh herbs. This will act as the rack for the bird. Place the bag in a roasting pan.
3. Place your turkey, breast-side up inside the bag. Use the enclosed oven-safe tie to secure the bag at the top. Snip six 1/2-inch-long slits in the bag with scissors – be sure to put one near a breast and a thigh, that way you can sneak your thermometer in to check the temperature.
4. Roast the turkey at 250°F (135°C) for about 15 minutes per pound (The roasting bag takes about 1 hour off the roasting time). For a 12-14 lb turkey, this will be approximately 3.5 to 4 hours
5. Use a meat thermometer to check the internal temperature, it needs to reach 170 to 180°F in the deepest part of the thigh.
6. Let the sealed bird rest for at least 30 minutes before cutting the top off the bag and peeling it down around the turkey.

If not using a roasting bag: 

1. Place the turkey breast-side down on a roasting rack in a large roasting pan.
2. Add 2-3 cups of broth to the bottom of the pan to keep the turkey moist.
3. Cover the turkey loosely with aluminum foil.
4. Roast the turkey at 250°F (135°C) for about 20 minutes per pound. For a 12-14 lb turkey, this will be approximately 4.5 to 5 hours. Baste the turkey with the pan drippings every hour.
5. Use a meat thermometer to check the internal temperature, it needs to reach 170 to 180°F in the deepest part of the thigh.
6. About 30 minutes before the end of the roasting time, increase the oven temperature to 450°F 
7. Flip the turkey over breast side up, baste and finish roasting so the skin browns.
8. Once done, remove the turkey from the oven and cover it loosely with foil. Let it rest for 20-30 minutes before carving to allow the juices to redistribute.

5. Make the Gravy:

1. After removing the turkey from the pan, pour the pan drippings through a fine mesh sieve to separate the fat from the liquid.
2. In a saucepan, heat 1/4 cup of the fat over medium heat. Whisk in the flour to make a roux, cooking for about 2 minutes until lightly golden.
3. Gradually whisk in the reserved pan drippings and additional broth (if needed) and dry white wine (optional)  until the gravy reaches your desired consistency.
4. Season with salt and pepper to taste.