CHOCOLATE GANACHE: Stir together heavy whipping cream and corn syrup in a microwave safe bowl. Heat on high power for 45 seconds. Pour chopped chocolate into hot cream and let sit for 3 minutes. Stir until smooth. If needed, heat for 10 second increments, stirring after each until melted. Allow to cool for 15 minutes then pour over top of the marshmallow cheesecake fluff.