1In food processor, place pesto ingredients. Cover; blend on medium speed about 1 minute, stopping occasionally to scrape down sides, until smooth. Set aside.
2Cook and drain pasta as directed on package. Return to saucepan; cover to keep warm.
3Meanwhile, in 10-inch skillet, heat oil over medium heat. Add onion; cook and stir 2 minutes. Stir in mushrooms, tomatoes, salt and pepper. Cook 5 minutes, stirring frequently, until mushrooms are tender and tomatoes are soft.
4Stir vegetables and pesto into pasta until evenly coated. Serve immediately.