Cook pasta in a large pot according to package directions.
Add asparagus to the pot during the final 2 minutes of cooking time.
Drain, reserving ½ cup cooking water.
Return the pasta mixture to the pot; stir in chicken, pesto, salt and pepper.
Stir in the reserved cooking water, 1 tablespoon at a time, to reach desired consistency.
Transfer the mixture to a serving dish; sprinkle with Parmesan and garnish with basil, if desired.
Serve immediately.
