I'm a mac and cheese snob because I consider mine the best ever. It's called "Aunt Gigi's Famous Macaroni and Cheese"

However it takes hours to make. The white sauce has to be brought to a boil which, even with a pampered chef non stick pot, takes 2 hours of constant stirring on low heat. If you stop stirring the bottom burns or lumps form. Then it has to boil for one minute. This prevents the sauce from separating when the casserole is baked.
Since I make large batches and freeze them unbaked to give as gifts to my family at Christmas, this step is very important.
The sauce contains butter, flour, milk and my secret ingredient, celery salt.
I use Cabots sharp cheese, and lots of it, and Barilla Cellentani (a corkscrew pasta) instead of elbow pasta.
A layer of pasta, topped with cheese, pour on some sauce, another layer of pasta, cheese, and sauce, then a final layer of cheese on top.
I recommend people to top it with chunks of italian bread for the last five minutes of baking, the chunks get a little toasty.
I like to throw some tomatoes in, when I'm having it at home, and I know various family members like to garnish theirs up when they bake them, too.
I love it leftover too, I heat leftovers up in a saucepan with a little butter and some milk, (bread and all) and it is oh so creamy and saucy that way.
Yummy.