01 - In a large mixing bowl, combine the instant pistachio pudding mix and undrained crushed pineapple. Stir thoroughly until the pudding mix is completely dissolved and the mixture begins to thicken.
02 - Fold in the mini marshmallows and chopped nuts if using. Use a rubber spatula to gently incorporate ingredients while maintaining the airy texture.
03 - Gently fold in the thawed whipped topping until fully combined. Continue folding until the mixture achieves a uniform, light, and fluffy consistency throughout.
04 - Cover the bowl and refrigerate for at least 1 hour before serving. This resting period allows the flavors to meld together and the marshmallows to soften properly.
05 - Just before serving, top with additional whipped topping, maraschino cherries, and extra chopped nuts as desired. Serve chilled.