01 - In a large mixing bowl, combine instant pistachio pudding mix with undrained crushed pineapple. Stir thoroughly until pudding mix dissolves completely.
02 - Fold in mini marshmallows and chopped nuts if using. Distribute evenly throughout the mixture.
03 - Gently fold in thawed whipped topping until fully incorporated. The mixture should appear light and fluffy with uniform color.
04 - Cover bowl and refrigerate for at least 1 hour before serving. This allows flavors to develop and marshmallows to soften properly.
05 - Just before serving, top with additional whipped topping, maraschino cherries, and extra chopped nuts as desired.