Let turkey stand at room temperature 1 hour. Preheat oven to 325℉ (160℃) with rack in lower third. Pat turkey dry with paper towels. Fill body cavity with 6 cups stuffing. Fill neck cavity with 4 cups stuffing. Secure skin flaps with toothpicks or skewers. Spread 6 tablespoons butter over top of Turkey, then season generously with salt and pepper. Tie drumsticks together with kitchen twine. Tuck wings under turkey.
Place a 40-inch (102cm) sheet of parchment on a work surface and spread with the remaining 2 tablespoons butter. Place the turkey on top, with a short side of the bird facing you. Gather ends, wrapping turkey. Fold overlapping ends of parchment over turkey and secure with staples.
Place a 48-inch (122cm) sheet of parchment on the work surface, place turkey on top, and rotate 90 degrees. Fold short parchment sides over turkey and secure with staples. Rotate bird another 90 degrees and repeat process with another 40-inch (102cm) sheet of parchment. Secure all paper flaps with staples.
Place turkey in parchment on a flat (not V-shaped) rack set inside a roasting pan. Roast turkey 2 hours, 45 minutes. Remove from oven; cut open parchment with scissors. Increase oven temperature to 425℉ (220℃). While holding drumsticks, slide parchment out from under turkey and discard. Return turkey to oven.
Continue to roast turkey until golden brown and a thermometer inserted in the breast reads 165℉ (75℃), about 45 minutes more. Transfer to a carving board and let rest at least 45 minutes and up to 1 hour before carving.
Meanwhile, remove stuffing from both cavities; transfer to an 8-inch-square (20cm square) baking dish and bake until thermometer inserted in center of stuffing reads at least 165℉ (75℃), 15 to 20 minutes. Using drippings in pan, make turkey gravy.