I receive a box of "commodities" every month. This includes a 2# block of low-fat American cheese. Since they also give me elbow macaroni, I usually make at least 1 casserole size batch using a cup of macaroni and lots of cheese.
I use a can of cream soup, celery, chicken, or mushroom to melt the cheese in then I add the one ingredient that makes it taste good, 1/2 cup of grated Parmesan cheese.
Because the American cheese is so bland, especially low-fat, the Parmesan adds that much needed bite.
I'd prefer to make it with nice cheddar, but cheese is expensive and this stuff is free.
I'll be making some tomorrow to go with the pork chili I made today, and this time I'll have some Asiago to add instead. I bought the Asiago to go in the Mushroom Gratin by LPBeier and the Asiago was very strong. I bet it will make a great mac & cheese add-in.
If you can't see the bright side of life, polish the dull side.