Bring a large pot of salted water to a boil over hight heat. Cook the pasta according to the package instructions, to your desired texture; either al dente or softer (I prefer softer). When the pasta is done, drain the pasta in a colander and rinse it under cold water. Set aside for later.
1 box (16 oz) rotini pasta
In a large mixing bowl, add the chopped chicken, drained pineapple tidbits (reserve the juice from the can), celery, grapes, green onions, and cashews. Stir together to combine.
3 cups cooked chopped chicken, 1 can (20 oz) pineapple tidbits, 1 cup finely diced celery, 1 cup halved red seedless grapes, 1 cup halved green seedless grapes, 1 cup thinly sliced green onions, 2 cups lightly salted cashew halves & pieces
In a separate smaller mixing bowl, whisk together all the ingredients for the creamy pineapple dressing.
1 cup ranch dressing, 1 cup mayonnaise, 1/3 cup reserved pineapple juice, ½ teaspoon kosher salt
Add the dressing into the larger bowl along with the drained and slightly cooled cooked rotini pasta. Stir everything together until it's well combined.
The salad can be served right away, but for best results, cover the bowl with a lid or plastic wrap and refrigerate for up to 4-6 hours before serving. The salad is best served chilled once it has had time to chill and the flavors to blend together.