1. In the bowl of a food processor combine the yogurt, olive oil, basil, garlic, parmesan cheese, pepper and salt. Process until all the ingredients are thoroughly mixed. Taste and adjust seasonings. Set aside.
2. Measure 1/2 of the sauce into a large bowl and set aside. Bring a large pot of water to boil. Season water with salt. Add the pasta and cook until al dente (about 12 minutes). Drain. Add the pasta gradually to the yogurt sauce. If you add it too quickly the sauce will break.
3. Garnish with basil leaves, chopped tomatoes and pine nuts if desired.