Cabrales Cheese, bought in the village of Arenas de Cabrales, in the Cabrales region of Spain. My favorite cheese.

These mature in cold and extremely humid caves in the rocks of the Picos de Europa mountain range (Asturias, Spain). The most expensive cheese ever sold was a Cabrales from Arenas de Cabrales (buying them from one of the manufacturers there isn't expensive, though)