How to Revive Hard Cheese
Cheese can harden and become difficult to grate long before it actually goes bad. Here's a great idea!
If your Parmesan is dry and difficult to grate, try this trick. Wrap the cheese in a damp paper towel, place it in a resealable plastic bag, and chill it for a day. Then remove the towel and store the cheese in the bag — it should be good to grate!