Place chicken breasts between two sheets of plastic wrap and gently pound to even thickness using a meat mallet or rolling pin.
In a small bowl, mix 1 tablespoon olive oil, garlic powder, oregano, salt, and pepper. Rub mixture evenly over both sides of the chicken.
Grill chicken for 6–7 minutes per side, or until internal temperature reaches 165°F (74°C). Remove from grill and let rest for 5 minutes.
While chicken rests, prepare bruschetta: In a medium bowl, combine diced tomatoes, basil, minced garlic, remaining 1 tablespoon olive oil, balsamic vinegar, red pepper flakes (if using), salt, and pepper. Stir gently and let sit for 5–10 minutes to allow flavors to meld.
Slice chicken breasts and top each with a generous portion of bruschetta mixture. Drizzle with balsamic glaze if desired.
Serve immediately with a side of crusty bread or a fresh green salad.
Notes
For best results, use ripe, in-season tomatoes. The balsamic glaze adds a touch of sweetness and visual appeal but can be omitted if preferred.