Preheat oven to 350°F (177°C). Pat chicken breast dry with a paper towel. Season with salt and pepper on both sides. In a skillet over medium-high heat, warm 1 tablespoon olive oil until hot. Cook chicken in the skillet until cooked through, about 6 to 8 minutes per side. Transfer to a plate to cool slightly. When cooled, cut into ½-inch pieces.
Arrange bread slices on two baking sheets. Drizzle with olive oil and season with salt and pepper to taste. Chop basil leaves finely, and sprinkle over bread slices. Arrange slices of mozzarella on the bread. Top with tomatoes and chicken. Sprinkle with salt and pepper.
Bake 10 to 15 minutes, or until cheese is melted and slightly bubbly. Remove from oven and let cool 2 minutes before eating.