Cook the high-protein pasta in salted boiling water according to package instructions until al dente.

Drain the pasta and rinse immediately with cold water to cool, then drain thoroughly.

In a medium bowl, whisk together the Greek yogurt, milk, and dry ranch seasoning until smooth.

In a large mixing bowl, combine the cooled pasta, chicken, tomatoes, cucumber, onion, and bell pepper.

Add the yogurt dressing to the pasta mixture and fold gently until all components are thoroughly coated.

Garnish with fresh parsley and refrigerate for 30 minutes to set before serving.