Parmigiano-Reggiano is a hard, salty, granular, cows milk cheese that is cooked but not pressed. It is named after the regions of Parma, Reggio Emilia, Modena, and Bologna, and Mantova, Italy -- as under Italian law only cheese produced in these provinces may be labelled Parmigiano-Reggiano. Aged approximately two years, a good parmigiano is as essential to cooking as a good olive oil.