Cook's Illustrated Macaroni and Cheese

So this is comfort food, and probably my favorite recipe for homemade mac and cheese in the world.  Guess where it's from...Cook's Illustrated.  I know, I am totally predictable, but I do like their recipes so much.  Anyway, I don't follow their recipe exactly, so this is how I do it, and unfortunately it is a calorie bomb.  Each serving is 567 calories, and it is pure deliciousness :).  We all gave this a perfect 10, except Aaron who gave it an 8 because he doesn't like home made mac n cheese.  Here's what I do:

1 lb macaroni
salt
5 T unsalted butter
6 T flour
1/2 t dry mustard
5 c milk (whole milk is what I used)
12 oz (3 cups) grated Monterey Jack cheese
12 oz (3 cups) grated sharp cheddar cheese

Cook the macaroni in well salted water until the pasta is tender.  Drain it and set aside.  Heat the butter in a large Dutch oven or pot and whisk in the flour and mustard.  Continue whisking as the mixture becomes fragrant, then add the milk, bring it to a boil, and then let it thicken, whisking, about 5 minutes.  Add in the cheeses and salt to taste, then mix in the macaroni.  Let settle about 10 minutes, then serve.