Cook pasta according to the directions on the box.
In the meantime, prepare the sauce.
In the bowl of your food processor combine avocado, basil, onions, cilantro or parsley, lime juice, yogurt, water, salt and pepper; process until creamy and smooth. Set aside.
Drain cooked pasta; return to pot.
Stir in the basil-avocado sauce and mix until thoroughly combined.
Garnish with parmesan shavings.
Serve immediately.
Notes
If the sauce is too thick for your liking, add 1 more tablespoon of water.