Bring a large pot of salted water to a boil and cook the cheese tortellini according to package instructions until tender.
Drain the tortellini and rinse gently under cold water until completely cooled.
While the pasta cooks, season the chicken breasts with olive oil, Italian seasoning, salt, and black pepper.
Heat a large skillet over medium-high heat and cook the chicken for about 5–6 minutes per side until golden brown and fully cooked through.
Remove the chicken from the skillet and let it rest for several minutes before slicing into strips.
In a large mixing bowl, combine the cooled tortellini, cherry tomatoes, mozzarella pearls, sun-dried tomatoes, and pine nuts.
In a small bowl, whisk together basil pesto, olive oil, lemon juice, Parmesan cheese, salt, and black pepper until smooth.
Pour the pesto dressing over the pasta mixture and toss gently until evenly coated.
Arrange the sliced chicken over the pasta salad and sprinkle with fresh basil.
Cover and refrigerate for at least 20–30 minutes before serving for the best flavor.
Toss lightly again before serving and garnish with extra Parmesan or pine nuts if desired.