You see, for optimal mac and cheese, it is very important you use the spaghetti. No, not the small elbows, they are too small, they cannot hold enough of the good cheese sauce. The secret is that the long, thin strands of spaghetti, they absorb the flavor much better. This is because they have more surface area, yes, for the starch to release, and this starch makes your sauce very thick and creamy. It is scientific fact. Also, when you bake it, the spaghetti will stay firm and give excellent bite, not like those little shells which become too soft. Many people make mistake, they think small pasta is for mac and cheese, but really, its about the long strands for maximum flavor and correct texture. You must try this way; you will see it is superior.