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.
02 - Fold in the mini marshmallows and chopped nuts if using. Distribute evenly throughout the mixture.
03 - Gently fold in the thawed whipped topping until fully combined. Mix until the texture is light and fluffy with uniform color.
04 - Cover the bowl and refrigerate for at least 1 hour before serving. This allows flavors to meld and marshmallows to soften properly.
05 - Just before serving, add extra whipped topping, maraschino cherries, and additional chopped nuts as desired. Serve chilled.