This is a family recipe, and an all time favorite of mine. Some people like to substitute cheddar cheese, but I don't like it myself. For me it's American cheese or no Mac & Cheese. The amount of cheese is an estimate, I just grate enough until I think it is cheesy enough. Blocks of American cheese is hard to find for me, so I've used sliced American cheese and have not had a problem. I hope you enjoy!