01 - Preheat oven to 400°F. Lightly grease a baking dish or sheet pan.
02 - Pat chicken breasts dry. Rub with olive oil, salt, pepper, and Italian seasoning. Place in the prepared baking dish.
03 - Spoon 1 tablespoon pesto over each chicken breast, spreading evenly.
04 - Bake for 15 minutes.
05 - In a medium bowl, combine diced tomatoes, red onion, garlic, basil, olive oil, balsamic vinegar, salt, and pepper. Toss well and set aside.
06 - After 15 minutes, remove chicken from the oven. Top each breast with a quarter of the bruschetta mixture and sprinkle evenly with shredded mozzarella.
07 - Return to oven and bake for another 8–10 minutes, or until chicken is cooked through (internal temp 165°F) and cheese is melted and bubbly.
08 - Let rest for 3–5 minutes before serving. Serve with any remaining bruschetta topping.