Bring a large pot of salted water to a rolling boil. Add the rotini pasta and cook according to package directions, cooking 1-2 minutes longer than al dente to ensure the pasta stays tender after refrigeration. The pasta should be fully cooked but still have a slight bite.

Drain the cooked pasta thoroughly and immediately rinse with cold water to stop the cooking process and cool the pasta down. This step is crucial - never add fresh vegetables or creamy dressing to hot pasta as it will wilt the vegetables and cause the dressing to separate.

Transfer the cooled pasta to a large mixing bowl. Add the halved cherry tomatoes, broccoli florets, diced cucumber, diced red bell pepper, chopped cooked bacon, chopped red onions, and sliced black olives. Toss gently to distribute the ingredients evenly.

In a separate small bowl, combine the mayonnaise, sour cream, and ranch dressing mix. Whisk until smooth and well combined. Season with salt and pepper to taste, adjusting the flavors as desired.

Pour the creamy ranch dressing over the pasta and vegetable mixture. Toss everything together until the pasta is fully coated and all ingredients are evenly distributed. The pasta should be well-coated but not swimming in dressing.

Cover the bowl with plastic wrap and refrigerate for at least 1 hour to allow the flavors to meld and the pasta to absorb the creamy dressing. Garnish with fresh parsley before serving cold.