Spray 10-inch skillet with cooking spray; heat over medium-high heat. Add chicken and pesto; cook and stir 10 minutes or until chicken is no longer pink in center. Transfer cooked chicken to plate; set aside.
Meanwhile, cook pasta as directed on package; drain.
Spray same skillet again with cooking spray. Add garlic and zucchini; if desired, season with salt and pepper. Cook and stir 5 minutes. Add tomatoes; cover and cook about 3 minutes or until tomatoes are hot and zucchini is tender.
Add cooked pasta and chicken to skillet; gently toss to combine. Serve immediately.