Preheat your oven to 400°F (200°C).
In a large bowl, toss the zucchini, yellow squash, bell pepper, and red onion with 1 tablespoon of olive oil, half of the Italian herbs, salt, and pepper.
Rub the chicken breasts with the remaining olive oil and Italian herbs. Season with salt and pepper.
Arrange the vegetables and chicken breasts on a baking sheet in a single layer. Place in the oven and roast for about 30-35 minutes.
Garnish with fresh basil or parsley if desired. Serve hot.
