Preheat the oven to 450°.
Arrange the baguette slices on a baking sheet, brush with some of the olive oil and sprinkle with salt. Bake until the bread is pale golden and crisp, about 5 minutes. Top each slice of bread with a slice of tomato and sprinkle with salt and pepper. Top with a slice of mozzarella cheese and sprinkle with salt. Return the baking sheet to the oven until the cheese and tomato are just warm, about 5 minutes.
Arrange the toasts on a serving platter. Top each toast with a basil leaf. Using the brush, drizzle the remaining olive oil over the basil. Sprinkle with salt and pepper, and serve. Makes 4 to 6 servings.