Line extra-large pot with two 13-gallon plastic bags, 1 inside the other (or use a brining bag).
Apple Cider (4 cups)
Kosher Salt (1 1/2 cups)
Whole Allspice (1/4 cup)
Bay Leaves (8)
in a 20-quart pot for 5 minutes, stirring until salt dissolves.
Remove from heat, add remaining
Apple Cider (8 cups)
Water (16 cups)
. Pour brine into the plastic bag.
Wrap turkey neck and refrigerate. Submerge
Whole Turkey (1)
in brine to cover completely, gathering bags tightly to eliminate any air; tie bags closed. Refrigerate turkey in brine in the pot for at least 18 hours and up to 20 hours.
The next day, line a large roasting pan with 4 layers of paper towels. Remove turkey from brine and drain well; discard brine. Place turkey in prepared pan. Cover with plastic wrap and refrigerate overnight.
Chicken Broth (4 cups)
Apple Cider (2 cups)
in a heavy large saucepan. Boil until reduced to 3 cups, about 20 minutes. Pour broth reduction into a bowl.
Unsalted Butter (1/4 cup)
in the same saucepan over medium-high heat. Add
All-Purpose Flour (1/4 cup)
and stir for 1 minute.
Whisk in broth reduction, then
Whipping Cream (1/2 cup)
Calvados Apple Brandy (2 Tbsp)
Italian Flat-Leaf Parsley (2 Tbsp)
Fresh Thyme (2 Tbsp)
Fresh Sage (2 Tbsp)
Fresh Marjoram (2 Tbsp)
Fresh Rosemary (1 tsp)
Ground Nutmeg (1 tsp)
. Bring to a boil.
Reduce heat to medium-low and simmer until gravy base is thickened and reduced to 2 3/4 cups, whisking often about 20 minutes. Cool gravy base, cover, and chill.
Position rack in the bottom third of the oven and preheat to 350 degrees F (180 degrees F).
Remove turkey from roasting pan; drain any accumulated juices from the main cavity. Discard paper towels from the roasting pan. Return turkey to prepared pan. Tuck wing tips under; tie legs together loosely to hold shape.
Granny Smith Apples (2)
in the main cavity. Scatter remaining apples and onions around the turkey in the pan. Add reserved turkey neck to the pan along with
Chicken Broth (1 cup)
Fold a 2-yard piece of cheesecloth to create a 4 layer rectangle. Dampen the cloth with water and wring out.
Unsalted Butter (2 sticks)
and then submerge the cloth in the melted butter, making sure it is completely saturated. Drape over the top of the turkey, covering it completely.
Roast turkey for 1 hour. Baste with
Apple Cider (1/2 cup)
. Roast turkey for 30 minutes.
Baste with remaining
Apple Cider (1/2 cup)
. Roast turkey, basting every 30 minutes with pan juices for another 1 1/2 hours.
Very gently remove the cheesecloth from the turkey, taking care not to tear the skin. Baste turkey one more time, then return the turkey to the oven and roast until a thermometer inserted in the thickest part of a thigh measures 170 degrees F (77 degrees C), about another 30-45 minutes.
When done roasting, transfer turkey to a platter; let stand at least 30 minutes before carving (internal temperature will rise 5-10 degrees).
Discard apples, onions, and turkey neck from the pan. Pour pan juices into a large glass measuring cup; spoon off fat from the surface.
Pour degreased juices into gravy base and bring to boil over medium-high heat, whisking occasionally. Boil until gravy thickens enough to coat a spoon and is reduced to 3 1/2 cups, about 15 minutes. Season gravy to taste with
Ground Black Pepper (to taste)
Serve turkey with gravy.