Lay the skin flat on the work surface. In a large bowl, combine the meat and fat and spices. Place the mixture in the center of the square and, using a trussing needle and butcher's twine or sausage casing that has been twisted into a thread, fold the square and sew it to resemble a 3-cornered priest's hat, making sure that all the filling is well-encased within the skin.
Bring 6 quarts of water to a boil. Prick the outside of the capello lightly with the needle, taking care not to completely puncture the skin. Wrap the capello in cheesecloth and boil, covered for 2 hours -- adding more water if necessary. Drain, pat dry, remove from the cheesecloth and serve in thick slices.