Bring a pot of salted water to a boil over medium-high heat, add the rotini pasta, and cook for 8-10 minutes until al dente. Drain and rinse under cold water.

In a large mixing bowl, combine the cooked chicken, green and red bell peppers, Roma tomatoes, olives, corn, red onion, black beans, and pinto beans. Add the taco seasoning mix and stir well.

Gently fold the cooled pasta into the chicken and vegetable mixture until evenly distributed.

In a smaller bowl, whisk together the mayonnaise, sour cream, salsa, buttermilk, and fiesta ranch dip seasoning until smooth.

Pour the dressing over the pasta and chicken mixture, gently fold until evenly coated.

Fold in the Colby Jack cheese and refrigerate for at least 2-4 hours before serving.