Preheat the oven to 200° C (390° F).
If using a frozen turkey, let it totally defrost following the instructions above. If your turkey is fresh, remove it from its packaging, and dry it off with some paper towels.
Season the cavity with the ⅓ of the salt and pepper, and stuff it with a halved onion and apple, quartered lemon, and herbs.
Mix together the softened butter with the other ⅓ of the seasoning in a small bowl.
Separate and loosen the skin carefully from the breast, and spread ¾ of the mixture, massaging gently.
Place the halved onions, garlic heads, roughly chopped celery, and carrots along with the bay leaves and thyme in a large baking dish.
Rub the remaining butter all over the turkey breast, and sprinkle on the rest of the seasoning.
Use string to tie the turkey legs together if it is not already done by your butcher, and place the turkey on top of the vegetables, breast side down.