Prepare a 10″ graham cracker crust. In a large bowl, combine 1 cup of thawed, drained frozen strawberries or raspberries, 1 cup sugar, 2 egg whites and 1 tablespoon lemon juice. Beat at least 15 minutes to create a fluffy mixture. In a small bowl whip 1/2 cup whipping cream. Add 1 teaspoon vanilla. Fold whipped cream into the berry mixture. Pile into the prepared crust. Decorate with whipped cream, if desired. Freeze. Remove from freezer just before serving.
Serves 8 generously.