Bring a large pot of salted water to a boil and cook the rotini pasta according to the package instructions until tender.
Drain the pasta and rinse it lightly with cold water to stop the cooking process and cool it down quickly.
Set the pasta aside to drain completely while preparing the remaining ingredients.
Season the cooked chicken pieces lightly with salt, black pepper, and garlic powder for extra flavor if desired.
In a small bowl, whisk together Caesar dressing, sour cream, lemon juice, garlic powder, and black pepper until smooth and creamy.
In a large mixing bowl, combine the cooled pasta, chopped romaine lettuce, cubed chicken, and parmesan cheese.
Pour the Caesar dressing mixture over the salad ingredients and toss gently until everything is evenly coated.
Add the croutons right before serving to keep them crunchy.
Sprinkle extra parmesan cheese and black pepper over the top if desired.
Serve immediately or refrigerate for about 30 minutes before serving for a colder pasta salad texture.