1. Preheat oven to 375 degrees Fahrenheit. Grease a baking pan with olive oil spray.
2. Toss peppers and onion in a large bowl.
3. In a small bowl, combine balsamic vinegar, Worcestershire sauce, olive oil, chicken broth, garlic, and herbs. Pour sauce over vegetables and toss well to coat.
4. Place the split chicken breasts in the bottom of prepared baking pan.
5. Pour vegetable/balsamic mixture over chicken and arrange peppers and onions evenly on top. Use every last drop of sauce.
6. Loosely cover the pan with a piece of foil and place in the center of the oven. Bake for 20 minutes.
7. Baste the chicken and vegetables with sauce (to keep it moist). Cover again and continue to bake until everything is melt-in-your-mouth tender, about 15 to 20 minutes more.