Cook the rotini pasta according to package instructions until al dente. Drain and rinse under cold water to cool.
In a large pot, bring water to a boil and add the broccoli florets. Blanch for 2-3 minutes until bright green, then drain and immediately place in ice water to stop cooking. Drain again and set aside.
In a large mixing bowl, combine the cooled pasta, blanched broccoli, cherry tomatoes, and grated Parmesan cheese.
In a separate small bowl, whisk together the Caesar dressing, mayonnaise, garlic powder, black pepper, and salt until smooth.
Pour the dressing mixture over the pasta and vegetables, tossing gently to coat everything evenly.
If using, sprinkle croutons on top for added crunch.
Garnish with fresh parsley if desired and serve immediately, or chill in the refrigerator for 30 minutes before serving for enhanced flavors.