Cover; process on medium speed about 1 minute, stopping occasionally to scrape down sides, until smooth.
Set aside.
Cook and drain pasta as directed on box.
Return to saucepan or stockpot.
Meanwhile, in 10-inch skillet, heat oil over medium heat.
Add onion; cook and stir 2 minutes.
Stir in mushrooms, tomatoes, salt and pepper.
Cook and stir 5 minutes or until mushrooms are tender and tomatoes are soft.
Stir vegetables and pesto into pasta until evenly coated in pesto.
Transfer to serving dish.
Notes / Tips / Wine Advice:
This colorful pasta dish is a perfect choice when entertaining friends or family. Only you need to know how easy it is to prepare! You can substitute campanelle pasta (small bells or flowers) if orecchiette isn’t available.