Guanciale

Guanciale is an Italian salt-cured meat product prepared from pork jowl or cheeks. Its name is derived from guancia, 'cheek'. Its rendered fat gives flavour to and thickens the sauce of pasta dishes. Guanciale is usually rubbed with just salt and ground black pepper by cooks in Rome, but some producers use other spices, herbs, peperoncino or red pepper, and sometimes garlic. It is cured for three weeks or until it loses approximately 30% of its original weight. Its flavour is stronger than other pork products, such as pancetta, and its texture is more delicate. When cooked, the fat typically melts away. Guanciale may be cut and eaten directly in small portions, but is often used as an ingredient in pasta dishes such as spaghetti alla carbonara and sauces such as sugo all'amatriciana.

Source: Wikipedia