Make the ranch dressing. Whisk all dressing ingredients together in a bowl until smooth. Taste and adjust seasoning. Refrigerate until ready to use.
Cook and cool the pasta. Cook rotini according to package directions, drain, and spread on a baking sheet to cool completely before assembling.
Assemble. Add the cooled pasta to a large bowl. Top with the cherry tomatoes, cucumber, bacon, chicken, hard boiled eggs, avocado, blue cheese, and cheddar.
Dress and finish. Pour the ranch dressing over the salad and toss gently to combine. Top with crumbled croutons right before serving. Season with salt and pepper to taste.