Place basil leaves in small batches in food processor and whip until well chopped( do about 3/4 cup at a time). Add a third of the nuts & garlic, blend again. Add a third of the parmesan cheese, blend all together while slowly adding a third of the olive oil, stopping to scrape down sides of container.
Process until it forms a thick smooth paste. Repeat until all ingredients are used, mix all batches together well. Serve over pasta. Keeps in refrigerator one week, or may be frozen.