Start the bruschetta by combining the chopped tomatoes with salt and garlic in a mixing bowl; mix well and let sit while the chicken cooks.
Place one chicken breast onto parchment paper, fold over, and pound to an even thickness of just under 1 inch. Repeat with all chicken breasts.
In a small bowl, combine italian seasoning, salt, garlic powder, onion powder, and pepper.
Brush chicken breasts with olive oil, then evenly sprinkle seasoning blend on both sides.
To Grill: Heat grill or grill pan over high heat. Cook chicken 5-6 minutes per side until internal temperature reaches 165°F. Remove and rest for 5 minutes.
To Bake: Preheat oven to 400°F and line a baking sheet with parchment paper. Roast chicken 10-12 minutes until internal temperature is 165°F. Remove and rest for 5 minutes.
Finish the bruschetta topping by stirring in olive oil, balsamic vinegar, fresh basil, and ground pepper to taste. Adjust seasoning if needed.
Top cooked chicken breasts with bruschetta mixture and drizzle with balsamic glaze if desired. Serve immediately.