Parmigiano-Reggiano & Grana Padano
Both of these classic Italian cheeses have been in production for at least 800 years. Mantua is the only province to make both.
Grana Padano comes predominantly from north of the River Po. It's made from the semi-skimmed product of two milkings on the same day, cooked twice, the second time at a higher temperature.
Parmigiano-Reggiano is made from the semi-skimmed milk of an evening's milking which is added to whole milk the following morning and cooked once.
Never buy 'Parmesan' ready grated in those cardboard tubes. It tastes like vomit.
Buy a chunk of rind-on cheese Grana Padano or Parmiggiano and store it in greaseproof or parchment paper in the refrigerator. When you reach the rind, freeze it for when you make a minestrone and add it to the broth to flavor it even more, removing it before you serve the soup. Vace and Whole Foods sell the rinds.