Place the foie gras in a snug container. Add enough milk to cover, and place in the refrigerator overnight.
The next day, drain and rinse the liver in cold water, then pat dry. Allow to come to room temperature.
Carefully separate the two lobes of the liver. Using a paring knife, carefully cut into the liver and remove the veins. Place the liver in a shallow baking dish and press it into an even layer about 1-inch thick.
Mix together the quatre epice, kosher salt and sugar and season the liver evenly. Cover with plastic wrap, pressing it tightly on top to keep the air out. Refrigerate overnight.
The next day, remove the liver from the refrigerator and again bring to room temperature. Place on a sheet of parchment paper and roll into a tight tube about 8-inches long. Remove from the parchment paper and place it on a length of cheesecloth. Again, roll into a tube as tightly as possible. Twist the ends, then tie with kitchen twine.
In a saucepan large enough to fit the liver, bring two quarts of chicken stock to a boil. Have a bowl of ice water large enough to fit the liver on hand. Carefully lower the liver into the boiling stock and simmer for 90 seconds. Immediately remove from the stock and place it in the ice bath. Allow to cool completely.
Once cooled, remove the liver from the ice bath and roll it up in a clean dish towel. Tie the ends with kitchen twine and hang it up, if possible, in the refrigerator overnight.
To serve, remove the foie gras from the kitchen towel and cheesecloth. With a warm knife, slice into desired thickness. Serve on toasted rounds of brioche bread. Drizzle with the cranberry gastrique (recipe below).