In a bowl, add cool whip and dry pistachio pudding mix. Mix until well blended.
Then add pineapple and cottage cheese; mix well. If you like really soft marshmallows add them at this point, if you like more firm marshmallows, mix in just before serving (I like mine soft).
Refrigerate for at least 1 hour before serving. Mix in additional chopped pistachios before serving if desired.