01 - Preheat oven to 400°F. Lightly grease a baking dish or sheet pan with cooking spray or oil.
02 - Pat chicken breasts dry with paper towels. Rub with olive oil, then season evenly with salt, pepper, and Italian seasoning. Place seasoned chicken in the prepared baking dish.
03 - Spoon 1 tablespoon pesto over each chicken breast, spreading evenly to cover the top surface.
04 - Bake chicken for 15 minutes to begin cooking process.
05 - While chicken bakes, combine diced tomatoes, red onion, garlic, basil, olive oil, balsamic vinegar, salt, and pepper in a medium bowl. Toss thoroughly to combine and set aside.
06 - Remove chicken from oven after 15 minutes. Top each breast with one-quarter of the bruschetta mixture, then sprinkle shredded mozzarella evenly over all pieces.
07 - Return to oven and bake for 8-10 minutes, until chicken reaches internal temperature of 165°F and cheese is melted and lightly browned.
08 - Let chicken rest for 3-5 minutes before serving. Serve with any remaining bruschetta topping spooned over the top.