Bring a large pot of salted water to a boil and cook pasta as desired. Drain.
While spaghetti is cooking, in a medium bowl, season diced chicken with Italian seasoning, salt and pepper to taste.
In a large skillet, heat olive oil until shimmering. Brown chicken and cook through. Remove chicken to a bowl and set aside.
If adding zucchini, add to skillet and sauté until just barely fork tender. Remove to bowl with chicken.
In a large bowl, combine cooked pasta, chicken, zucchini, cherry tomatoes and pesto. Toss to combine.
Serve topped with a little grated Parmesan cheese and chopped fresh parsley if desired.