Remove giblets and neck from body cavity of turkey. Save to enhance broth and gravy, if desired.
Rinse bird thoroughly with cold water and pat dry with paper towel. Spoon enough stuffing into the cavity to fill without packing it in, as stuffing expands as it heats. Return legs to tucked position, and secure with kitchen twine. Save any leftover stuffing, and bake alongside turkey in a baking dish.
Preheat oven to 350 F (175 C).
Place breast-side down in a roasting pan. Rub butter over turkey and season with Turkey Seasoning (poultry seasoning, rosemary and/or thyme). Coarsely grind salt and pepper overtop.
Roast, basting occasionally, for 15 – 20 minutes per 1 lb (450 g). Depending on size of turkey, this may take anywhere from 3 1/2 to 4 1/2 hours. Turkey is done when drumsticks move easily at joints and an instant-read thermometer inserted into thigh reads 180 F (82 C). If turkey is browning too quickly, loosely cover with a foil tent.
Remove turkey from oven. Using a spoon, remove stuffing and transfer to a bowl and cover to keep warm. Cover turkey with foil, and let stand at least 15 minutes before carving.
NOTE: when purchasing a turkey, 1 lb per person is a good guideline.