Bring 6 cups water to a boil in a large pot. Add the 2 cups pasta and cook about 11 minutes or until tender, following package directions.
Drain the pasta in a colander and return to the pot or a large bowl; drizzle with 1/2 tablespoon olive oil and toss to prevent sticking. Let the pasta cool to room temperature, then chill in the refrigerator until fully cool.
In a large mixing bowl, combine 1 cup Greek yogurt, 1/2 cup mayonnaise, 2 tablespoons ranch dry mix, 1 teaspoon dried parsley (or 2 tablespoons fresh), 1/4 teaspoon salt, and 1/4–1/2 teaspoon black pepper.
Add the cooled pasta, about 2 cups cubed rotisserie chicken, 4–6 chopped green onions, 1 cup shredded Colby Jack cheese, and 1 cup peas to the dressing. Stir until everything is evenly coated.
Cover and chill the pasta salad until very cold, then taste and adjust seasoning with more salt, pepper, or mayonnaise if desired.
Store leftovers in the refrigerator promptly and stir in a little mayonnaise before serving again if the salad seems dry.