1Heat the juice in a medium saucepan over low heat. Stir in gelatin until dissolved. Cook, stirring occasionally, until thickened, about 20 minutes. Transfer to a medium bowl and beat with an electric mixer until fluffy.
2In a blender, finely chop the cranberry sauce. Add the gelatin mixture and ice cream and mix until well blended.
3Transfer the gelatin mixture to the prepared crust. Cover and chill in refrigerator for 3 hours.
4Serve topped with sweetened whipped cream or non-dairy topping, if desired.