Guanciale is an Italian bacon made from the pig's cheek (also known as face bacon). Of course best known for the spaghetti alla carbonara! But the possibilities of use are so much greater!
The bacon has a very intense flavor but a very delicate texture. The fat melts very quickly, which makes it so suitable in sauces such as carbonara. In which the emulsion of water, egg and fat cause the sauce to bind.
The intense flavor is because of the movement of the cheek. The pig's cheek is going through a lot of movement, by chewing. And the more movement, the more flavor. In addition, the taste is enhanced by a long maturation and the addition of herbs and spices.