Cook the rotini pasta according to package instructions until al dente. Drain and rinse under cold water to cool.
In a large mixing bowl, combine the cooled pasta, cherry tomatoes, cucumber, red bell pepper, red onion, and thawed peas.
In a separate bowl, whisk together the ranch dressing, garlic powder, and black pepper.
Pour the dressing mixture over the pasta and vegetables. Toss gently to combine until everything is evenly coated.
Fold in the shredded cheddar cheese and fresh parsley, if using.
Cover the salad and refrigerate for at least 30 minutes to allow the flavors to meld.
Serve chilled or at room temperature.