This is a Giada recipe from The Everyday Italian cookbook. The secret to making pesto into a great pasta dressing is to get the sauce to the right consistancy. From the food processor, pestos are usually to thick to coat pastas; you'll just end up with mounds of the sauce amid a lot of undressed noodles. You need to mix in just enough of the pasta cooking liquid to get the pesto to coat the pasta, but not so much that you've created pesto soup. This recipe is easy and oh soooo good!