Puree cottage cheese in a food processor until smooth.
Transfer the pureed cottage cheese to a large bowl and whisk in the dry Jell-o mix until thoroughly incorporated.
Use a rubber spatula to fold in the whipped topping until no streaks remain.
Fold in crushed pineapple and mini marshmallows.
Cover and refrigerate for at least 2 hours.
If desired, serve topped with a dollop of whipped cream or whipped topping and fresh pineapple slices