Bring a large pot of salted water to a boil. Add the penne pasta and cook according to package instructions until al dente.

Drain the pasta in a colander and rinse under cold water to cool it down.

In a blender or food processor, combine the basil leaves, pine nuts, Parmesan cheese, garlic, salt, and pepper.

With the motor running, slowly drizzle in the olive oil until the mixture is smooth and creamy.

In a large mixing bowl, combine the cooled pasta, pesto, cherry tomatoes, and mozzarella balls. Toss gently to combine.

Adjust seasoning with additional salt and pepper if needed.

Transfer the pasta salad to a serving bowl and garnish with chopped fresh basil. Serve immediately or chill in the refrigerator for 30 minutes before serving.