I am remembering my cousin Jessica's post about making sure to take the cheese packet out of the mac and cheese box before pouring the noodles into the water ... and reminiscent of that, I have another tip to add to the "Mac and Cheese" list.
Always check that you have all ingredients before cooking.
But, if you happen to not have milk, it's actually less of a problem than you might think. We added the right amount of butter, about a 1/2 tablespoon of water... and it worked.. JUST FINE. Less calories, and it tasted... really pretty much the same. I think I actually liked it more because it was less runny!
So if you ever find yourself halfway through making some yummy mac and cheese, only to find you don't have any milk... don't give up! You can still enjoy your yummy, over processed, completely fake cheese noodles ;)