Protected Designation of Origin (P.D.O) is a title given to many specialty Italian cheeses that can only be produced in a single region or place, in order to be considered authentic. Italy currently hosts 47 types of P.D.O cheese, one of which is P.D.O Formaggio di Fossa di Sogliano, a cheese with a history that goes back to Medieval times.

Fossa cheese was first made in the Italian village of Sogliano al Rubicone, and today, the cheese is aged in a cold, dark underground pit, the way it was done hundreds of years ago. These hidden grottos were chosen as a suitably cool environment for cheese to mature, and also hid the cheese from thieves roaming the Italian countryside.

To make formaggio di fossa, curd from cow or sheep milk is pressed, salted, and ripened for two to eight months before being placed inside smoky, straw-insulated pits. The cheese is then aged wrapped in canvas sacks for about three months, and the humidity and temperature give it a musky smell and pungent taste, though flavors can vary.

Formaggio di fossa can be mild, intense, spicy, or bitter, and is best with honey and fruit or used in pasta recipes. To buy it in Italy, head to the mountain communities of Appennino Cesenate and the provinces of Forli Cesena, Rimini, and Pesaro Urbin, or look online and at cheese shops near you; either way, keep an eye out for that P.D.O label.