In a medium bowl combine the cream cheese and powdered sugar until smooth. Then in a seperate bowl whip the whipping cream until fluffy. Then fold it into the cream cheese and powder sugar mix. Spread the cream mix into the pie shell. Now make the currant filling by combining the sugar, corn starch, water, and lemon juice in a medium kettle. Stir over medium heat until boiling. Then add the currants. Return to a boil for 2 minutes. Next cool the berry mix in the refrigerator. After an hour it's ready to spread over the cream cheese layer. Top with whipped cream if desired before serving.