Cut the pork fat and foie gras into dice, pound finely together then add the peelings of the truffles. Soften over a gentle heat then pass through a fine sieve.
Melt 500 g (1 lb 2 oz) of this mixture in a pan and add the peeled truffles cut in small quarters (reserve 12 nice slices of truffle for later use); season with salt and pepper and add a bayleaf. Allow to cook gently for 10 minutes, cover with a lid and allow to become cold. When quite cold, mix in the remainder of the truffled pork fat and foie gras mixture.
Empty the turkey carefully from a hole in its side then remove the bones of the breast; leave the skin of the neck very long. Stuff it with the prepared truffled forcemeat; slide the reserved slices of truffle under the skin of the breast. Keep in a refrigerator for 24-48 hours.
Truss the turkey and sew up the hole on its side. Cover the breast with slices of salt pork fat then wrap it completely in a sheet of strong buttered paper.
Roast the prepared turkey on the spit before a concentrated fire which should be kept at the same heat during the whole of the roasting process.
If the turkey is to be oven roasted, this is best carried out in an uncovered braising pan.
Allow approximately 35 minutes per 1 kg (2¼ lb) when spit roasting and 28 minutes per 1 kg (2¼ lb) for oven roasting.
Serve the turkey accompanied with the roasting juices well skimmed of fat or optionally, with a thin Sauce Périgueux.