Arrange the slices of bread in a single layer on a baking tray. Mix together the olive oil and garlic powder in a cup or small bowl. Brush onto the slices of bread. Cover each piece of bread with tomato slices then sprinkle with as much cheese as you like. Drizzle just a bit of the olive oil over the cheese.
Grill for 3 to 5 minutes until cheese is melted and bread is toasted. Make sure you keep an eye on it - it doesn't take long!