Cook the rotini according to package directions until al dente, then drain and rinse under cold water to cool and stop cooking.
In a large bowl, combine the cubed cooked chicken, halved green grapes, halved red grapes, and dried cranberries.
Add the cooled rotini to the bowl with the chicken and fruit, and gently toss to combine.
In a small bowl, whisk together the ranch dressing and mayonnaise until smooth.
Pour the dressing over the pasta mixture and toss until everything is evenly coated.
Cover and refrigerate the salad for at least 1 hour to chill and allow flavors to meld.
Just before serving, stir in the salted cashews to preserve their crunch.
