Add the tomatoes, 3 cloves of garlic (minced), 1 Tablespoon of Olive oil, balsamic vinegar, onion, and basil to a medium bowl. Stir until tomatoes are coated. Cover and set aside or place in refrigerator. When ready to serve- Cut the baguette into 1/2" slices. Add 3 Tablespoons of Olive oil to a small saucepan. Place on the stovetop and turn burner on medium heat. When oil begins to sizzle add 1 garlic clove cut in half. Let simmer for 30 seconds, then remove the saucepan from the heat. Brush both sides of the baguette slices with garlic-infused olive oil. Place the slices on a 9x13 baking sheet. Turn the oven onto broil and place the baking sheet in the oven. Allow the slices to broil for 2-3 minutes or until the tops are golden brown. (Make sure to watch closely). Flip the baguette slices over and place a slice of fresh mozzarella or a Tablespoon of shredded onto the top of the baguette slice. Put the baguettes back under the broiler for 1-2 minutes or until cheese has melted and turned golden. Remove the baguettes from the oven. Place a spoonful of the tomato mixture over the top of each slice and serve immediately. (Optional) Drizzle the tops of each with balsamic glaze.