Cook pasta according to package directions, then rinse under cold water and drain completely.
In a large bowl, whisk together Caesar dressing, sour cream, lemon juice, garlic powder, salt, and pepper.
Add the cooked and cooled pasta, shredded chicken, cherry tomatoes, Parmesan, croutons, and parsley.
Gently toss until all ingredients are evenly coated.
Refrigerate for at least 30 minutes before serving.
Top with extra croutons and parsley for garnish, if desired.