Preheat oven to 350°. Place flatbread on pizza pan or cookie sheet covered with foil. Using a spoon, spread the olive oil evenly onto the bread. Evenly sprinkle garlic powder on top of oil. Layer mozzarella onto flatbread. Fill in gaps with smaller pieces of mozzarella. Layer tomatoes on top of mozzarella. Layer basil and chicken on top. Bake for 15 minutes or until cheese slightly browns. Drizzle balsamic vinegar on top of flatbread. Allow to slightly cool before serving.