Never waste old cheese
My favourite cooking cheese is parmesan. It keeps for a very long time and you don’t need to use much to get a really intense, ‘cheesy’ flavour.
If you are buying parmesan, go for a block over the pre-grated or shaker type. You’ll get a much better quality cheese, it will keep really well, and even the crust or rind is useful to add to soups or stews.
Parmesan and cheddar cheese can be frozen. I place any small pieces of cheese that are going hard in my fridge into a plastic bag and pop them in the freezer. These are great as flavouring and for toppings. Put through a food processor to make a grated mix.