Bitto is an Italian DOP (Denominazione di Origine Protetta) cheese produced in the Valtelline valley in Lombardy. It owes its name to the Bitto stream in the valley. Since the quality of the grass animals feed on influences the taste, Bitto is produced only in the summer months when the cows feed on the high alpine meadows.
Bitto is made from whole cow's milk produced in the summer months around the Valtellina valley, to which must be added 10% to 20% goat's milk. Adding a higher percentage of goat's milk allows long aging of 10 years or more. However, due many uncontrollable factors, it is the dairyman's job to determine how long to age each Bitto wheel.