1. Rinse the turkey under running water and pat dry, then place it on a roasting pan. Gently run your fingers between the skin and the meat without breaking it, especially at the breast and drumstick areas.
2. Slide the cubes of butter under the skin slits, and secure them on the skin with a toothpick. Then, set the bird aside for seasoning.
3. Combine the chopped aromatics and vegetables with salt and pepper in a bowl. Then, line the turkey cavity with cheesecloth, enough that it’ll fall outside the cavity.
4. Stuff the vegetable mixture in the chicken’s lined cavity, and spread the leftovers on the roasting pan around the bird. Then, close the cheesecloth ends by twisting them.
5. Tip the bird upward, and pour the stock into the cavity, such that the runoff enters the pan. Then, truss the bird with twine, and cover it with foil.
6. Prep the oven to heat to 300F, and take the racks out, leaving the one at the lower position, so there’s room for the turkey to cook.
7. Put the pan in the heated oven and cook the turkey until the thickest region of the thigh reads 140F. This should take at least six hours to cook.
8. Remove the foil, pour the sherry over the bird, and add garlic powder, pepper, and salt. Then, roast the bird for another 30 minutes or until the skin grows crisp and dark.
9. When the bird reads 160F on the internal thermometer, take the pan out and let it sit for at least 30 minutes on a wooden carving board.
10. Remove the cavity lining with the stuffing in it, and empty it into a baking dish. Keep it in a 375F oven until serving time.

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