Bring a large pot of salted water to a boil. Add the rotini pasta and cook according to package directions until al dente (usually 8-10 minutes).
While the pasta cooks, prepare your vegetables: halve the cherry tomatoes, dice the cucumber and red bell pepper, finely chop the red onion, and chop the fresh parsley.
Drain the cooked pasta in a colander and rinse thoroughly with cold water to stop the cooking process and cool the pasta completely.
In a medium bowl, whisk together mayonnaise, sour cream, buttermilk, fresh dill, garlic powder, onion powder, dried chives, salt, and black pepper until smooth and well combined.
In a large mixing bowl, combine the cooled pasta, prepared vegetables, and chopped parsley.
Pour the ranch dressing over the pasta mixture and gently toss until everything is evenly coated.
Cover the bowl with plastic wrap and refrigerate for at least 1 hour to allow the flavors to meld.
Before serving, give the salad one final gentle stir and adjust seasoning with additional salt or pepper if needed.
