Chop Cranberries: Add the cranberries to a food processor and pulse until they are finely chopped, but not mushy.
Marinate: Pour the cranberries into a large bowl. Stir in the sugar and pineapple and mix well. Cover and refrigerate for one hour or longer.
Whip Cream: In a medium bowl, beat the cream cheese until smooth. Pour in the cream and whip until stiff peaks form.
Combine: Drain some of the juice from the cranberry mixture. Fold the whipped cream mixture into the salad. Fold in marshmallows.
Chill in the refrigerate for 3-4 hours (or overnight), before serving.
