Pre-heat oven to 400F degrees.
In a large sheet pan arrange chicken breasts (washed and towel dried).
Season each breast with oil (2 tbs), salt, pepper, onion powder and oregano.
Add to the sheet pan half pint of tomatoes (whole is fine) and garlic cloves.
Bake for 20-23 minutes, depending on the size and thickness of the breasts. Check internal temperature to make sure chicken is just about fully cooked.
Remove from oven and add in mozzarella cheese. Return to oven for an additional of 5-8 minutes.
Meanwhile in a small bowl whisk the remaining 2 tbsp of oil, balsamic vinegar and season with salt and pepper.
Cut the remaining tomatoes in half or quarters. Set aside
When chicken is done (meat thermometer register 165F degrees in thickest part of the breast) remove from oven. Top each breast with tomatoes and fresh basil. Season each breast with oil and balsamic mix and serve.