This super creamy mac and cheese dish feeds a crowd. It's very tasty and it's very easy to make. Be sure to let the dish sit for 15 minutes after you add the sauce to the noodles. You can keep it warm in the oven (covered) during this time if you like. If you don't have gruyere cheese, use a total of 16 oz of sharp cheddar or half sharp cheddar and half extra sharp cheddar. Don't leave out the american cheese. Since first posting, I have also made this with Fontina instead of gruyere, and skipped the american cheese and it was also very good.