Blanch basil leaves (if you wish to maintain greener color of pesto) as follows: Boil pot of water. Place basil in sieve, and plunge into water for about 15 seconds. Remove, and place briefly in ice cold water. Drain very well. Chop leaves. In blender or food processor, combine basil leaves, walnuts, cheese, and olive oil, adding olive oil a bit at a time. Season with pepper as desired. Cook pasta, and add pesto to pasta while still warm. Serve with reserved Parmesan cheese and crusty bread.
makes about 5 servings.