Preheat oven to 350°. In a small pan over medium heat, combine 2 tablespoons olive oil, the butter, and garlic; stir until butter melts, about 2 minutes.
Cut baguette into 1/2-inch cubes and put in a 10- by 15-inch baking pan. Pour oil mixture over bread and mix well. Bake until golden, 10 to 15 minutes. Remove from oven and let bread cool in pan.
In a bowl, mix remaining olive oil, the vinegar, salt, and pepper. Stir in tomatoes and bread cubes. Serve at room temperature in shallow bowls, garnished with basil.
Note: Nutritional analysis is per serving.