I discovered this by accident one night when I had the pasta cooking and discovered I had no milk, as the box (Kraft) called for.
So, I doubled the butter for moisture and also after draining the pasta I rinsed the pasta with as hot of water as the sink sprayer put out. Then before the water could drain off, I dumped the pasta into the pan, added the cheese powder and butter (I always melt the butter in a sauce pan first, and if I want saute onion and/or garlic in same pan. I haven’t used milk in it since! So much cheesier, and more buttery! I also play around with spices for a different taste…sometimes it’s awesome…sometimes, not so much…LOL
I’ve made this for family and friends, and always get about the same reply…“My Mac & cheese never tastes this good! How do you make it?”
Spices I like best with it, are garlic, sage (sparingly), parsley, red pepper (occassionally, if I want spicy) & oregano. I frequently throw in a can of tuna and green beans (well drained) for a one dish meal ready in minutes.
(Note: peas don’t taste so good in this, corn is okay…you may like it more than I do, though)
The key for the moisture, I have found is both melting the butter (Mom always just put the stick into the pan with the pasta…but that cools it down and takes forever to melt), and dumping the pasta into the pan before the water drains all off of it. Try it, you won’t be disappointed!
(Note: I’ve tried the microwave method several times, and it just doesn’t come out as good.)