Whisk together balsamic vinegar, honey, olive oil, garlic, Italian seasoning, salt, and pepper.
Add chicken to the mixture and marinate for at least 10 minutes.
Preheat oven to 400°F or heat an oven-safe skillet over medium-high heat.
Sear the chicken on both sides until lightly golden.
Add broccoli florets and tomatoes around the chicken, tossing carefully in the glaze.
Transfer to the oven and bake for 10–15 minutes, until the chicken reaches 165°F and the vegetables are tender.
Top with mozzarella and fresh basil if desired, then serve.