Boil apple cider and maple syrup in a heavy saucepan over medium-high heat until reduced to 1/2 cup (about 20 minutes). Remove from heat and mix in 1/2 of the thyme and marjoram and all of the lemon zest. Add the butter, and whisk until melted. Add salt and ground pepper to taste. Cover and refrigerate until cold (syrup can be made up to 2 days ahead).
Preheat oven to 375 degrees F (190 degrees C). Place oven rack in the lowest third of oven.
Wash and dry turkey, and place in a large roasting pan. Slide hand under skin of the breast to loosen. Rub 1/2 cup of the maple butter mix under the breast skin. If planning on stuffing turkey, do so now. Rub 1/4 cup of the maple butter mixture over the outside of the turkey. With kitchen string, tie legs of turkey together loosely.
Arrange the chopped onion, chopped celery, and chopped carrot around the turkey in the roasting pan. If desired, the neck and giblets may be added to the vegetables. Sprinkle the remaining thyme and marjoram over the vegetables, and pour the chicken stock into the pan.
Roast turkey 30 minutes in the preheated oven. Reduce oven temperature to 350 degrees F (175 degrees C), and cover turkey loosely with foil. Continue to roast, about 3 to 4 hours unstuffed or 4 to 5 hours stuffed, until the internal temperature of the thigh reaches 180 degrees F (80 degrees C) and stuffing reaches 165 degrees F (75 degrees C). Transfer turkey to a platter, and cover with foil. Reserve pan mixture for gravy. Allow turkey to sit about 25 minutes before removing stuffing and carving.
To Make Gravy: Strain pan juices into a measuring cup. Spoon fat from juices. Add enough chicken stock to make 3 cups. Transfer liquid to a heavy saucepan and bring to a boil. In a small bowl, mix reserved maple butter mixture with flour to form a paste, and whisk into the broth. Stir in thyme, bay leaf, and apple brandy. Boil until reduced and slightly thickened. Season with salt and pepper to taste.