Combine the pineapple and juice, pudding mix, marshmallows, and pistachios in a medium-size bowl. Mix well.
Add the thawed whipped topping and stir until everything is combined.
Cover and refrigerate for a minimum of 1 hour.
Optional, garnish with maraschino cherries and serve.
No pistachios, no problem. You can easily substitute chopped toasted pecans or other nuts.You can save a few calories by using the "lite" version of Cool Whip. Leftovers, if there are any, can be stored in the refrigerator for up to five days. I don't recommend freezing leftovers. You can make this pistachio dessert up to 24 hours ahead of time. Keep it tightly covered in the refrigerator until you are ready to serve it. If you are adding a maraschino cherry for a garnish, wait to add it until right before you serve the pudding. Otherwise, the cherry juice will drain all over your dessert. This recipe can easily be doubled, tripled, etc. if you are feeding a lot of folks!