Place chicken breasts on a large plate or shallow pan. Sprinkle with garlic powder, salt and pepper on both sides. Drizzle with balsamic and olive oil. Place in the refrigerator while you prepare remaining ingredients.
Heat oven to 350°F.
Thinly slice tomato and mozzarella cross-wise. Set aside.
Place chicken in a baking dish in a single layer, discarding the marinade. Bake for 15 minutes. Remove from oven.
Layer basil, tomatoes and cheese on top of the chicken. Place back in the oven and bake an additional 5-10 minutes or until chicken is cooked through.
If desired, place under the broiler for 2-3 minutes until cheese is bubbly and golden.