While it might not be the best-looking dish on the holiday table, it will be incredibly popular. Super sweet and creamy, this dish will work just as well as a side as it will as a dessert. We guarantee there won't be leftovers.
Pulse cranberries in a food processor until finely chopped but not mushy, 4 to 5 times. Transfer to a medium bowl; stir in sugar. Cover and chill 2 hours.
Stir crushed pineapple into chilled cranberry mixture; drain, discarding liquids.
Beat cream cheese with an electric mixer on high speed until soft and fluffy, about 1 minute. Add heavy cream; beat until stiff peaks form, 2 to 3 minutes.
Fold cream cheese mixture and marshmallows into cranberry mixture. Cover and refrigerate at least 1 hour or up to overnight. Serve chilled.