Cover the dried cranberries with boiling water. Let stand for 5 minutes and then drain.
In a medium heavy-bottomed saucepan, combine the sugar, flour and salt. Gradually stir in the milk and eggs. Cook over medium heat stirring constantly until the mixture thickens and boils. Boil and stir for about 2 minutes. Remove from heat.
Stir in the sour cream, butter and cranberries; pour mixture into the baked pastry shell. Cover with plastic wrap. Refrigerate overnight.
Whip the cream until soft peaks form, fold in the confectioners' sugar and vanilla. Swirl over top of the pie. Serve and enjoy!