Fold each pancetta and guanciale slice several times to form cubes, then thread them onto a skewer. Pepper generously. Slice the bread in half lengthwise.
Put the skewer under a hot broiler or on a grill over a moderate fire to cook. Every so often, blot the skewer with the cut sides of the bread, pressing down on the crumb so it absorbs the meat juices. Continue cooking and blot