Whenever you cook pasta, remove some of the pasta-cooking water (about 1/4 or 1/3 cup) just before draining. When you add the sauce of your choice to the pasta, add a little of the cooking liquid. This helps sauce to amalgamate; the starch in the water adds body and a kind of creaminess. An old Italian friend of mine instructed me in this finishing touch early on, and I would never, ever leave it out. It makes all the difference.