Preheat oven to 450°F.
Unroll pie crust and fit into a 9-inch tart pan with a removable fluted rim. Roll rolling pin over the rim to trim dough even with the rim. Sprinkle bottom and sides with 2 TBSP granulated sugar. Prick bottom and sides of shell numerous times. Chill shell 30 minutes.
Line shell with foil and fill with pie weights. Bake in preheated oven 9 to 12 minutes.
Lower oven temp to 325 degrees. Remove foil and weights. Bake shell another 5 to 10 minutes or until golden. Cool completely in pan.
In a bowl with an electric mixer beat the whipping cream until stiff peaks form. In another bowl beat mascarpone and sugar until well blended. Gently fold the whipped cream into the mascarpone mixture. Spoon mixture into shell, spreading evenly.
In a small saucepan simmer preserves and Cassis. Stir until reduced to about 3 tablespoons and pour over the berries, stirring to coat. Mound the berries on mascarpone cream. Tart may be made several hours ahead and chilled. Bring tart to room temperature and remove side of pan before serving.