Prepare the Stuffing:

1. Heat the milk in a small saucepan until it begins to boil. Season with salt and freshly ground black pepper, then stir in the bread crumbs. Cook over low heat for 3 to 4 minutes, stirring constantly, until a thick paste forms.
2. Transfer the bread mixture to a large bowl and let it cool slightly.
3. Add the finely chopped ham and parsley. Mix thoroughly until well combined.
4. Melt the butter in a large nonstick skillet over medium-low heat. Add the minced shallots and cook for approximately 3 minutes, until softened and lightly golden.
5. Add the diced chicken livers and cook for approximately 2 minutes, stirring frequently, until lightly seared on the outside. The livers will finish cooking inside the turkey.
6. Transfer the shallot and liver mixture to the bowl containing the bread mixture. Stir until combined.
7. Add the walnuts, cumin, cinnamon, cloves, cayenne pepper, nutmeg, salt, and black pepper. Mix well to distribute the seasonings evenly.
8. Drizzle the Cognac over the stuffing and add the grated truffle. Stir thoroughly. Let the mixture cool before stuffing the turkey.

Prepare and Roast the Turkey:

1. Preheat the oven to 325°F (163°C).
2. Pat the turkey dry with paper towels. Lightly season the outside with salt and black pepper.
3. Loosely fill the turkey cavity with the prepared stuffing immediately before roasting. Do not pack the stuffing tightly. Place any remaining stuffing in a separate baking dish and cook it until its center reaches 165°F (74°C).
4. Secure the cavity opening with kitchen twine or poultry skewers. Place the turkey breast-side up on a rack inside a large roasting pan and lightly brush the skin with cooking oil.
5. Roast for approximately 3 to 3 1/2 hours, basting occasionally with the pan juices. If the juices begin to burn, add 2 tablespoons of water at a time to the roasting pan.
6. If the skin becomes too dark before the turkey is fully cooked, loosely cover it with aluminum foil.
7. Check the internal temperature using a food thermometer. The thickest part of the breast, innermost thigh and wing, and center of the stuffing must each reach at least 165°F (74°C).
8. Remove the turkey from the oven, cover loosely with aluminum foil, and let it rest for approximately 20 minutes before carving.

Prepare the Gravy and Serve:

1. Transfer the turkey to a large serving platter. Pour the roasting juices through a strainer into a saucepan.
2. Let the juices stand for approximately 5 minutes, allowing the fat to rise to the surface. Skim off and discard the excess fat.
3. Season the gravy with salt and freshly ground black pepper, then bring it to a boil before serving.
4. For an elegant holiday presentation, serve the turkey with peeled, cooked chestnuts warmed in a little gravy. Serve the remaining gravy separately.