Kosec cheese, with a slightly piquant fresh taste, is one of the most well-known cheeses from Pustotnik farm.

During the ripening process, faint red smear appears on the rind of Kosec; the smear then slowly dries, creating a rich taste and smell. A red-brown colour of the rind indicates that the cheese is properly ripened; its ripeness also reflects in a pleasant, full, aromatic taste and a clean, distinctive smell.