Thaw pastry sheet at room temperature 30 minutes. Preheat oven to 400°F. Make a pattern by cutting a piece of paper into a heart 7" long by 7 1/2" wide.
Unfold pastry on lightly floured surface. Roll into 14"x10" rectangle. Use pattern to cut out 2 hearts in pastry sheet. Cut remaining pastry into small hearts, using small cookie cutter. Place pastry hearts on baking sheet. Sprinkle with 2 tablespoons sugar.
Bake 15 minutes or until golden. Remove from baking sheet and cool on wire rack.
Beat cream, confectioners' sugar, cocoa and liqueur in bowl until soft peaks form. Spread chocolate mixture on 1 large pastry heart to within 1/2" of edge.
Arrange 1/3 cup raspberries on chocolate mixture. Top with remaining large pastry heart, sugar-side up. Place tart on serving plate.
Place remaining raspberries and remaining sugar in blender jar. Cover and blend until smooth. Spoon sauce around edge of tart and garnish with small pastry hearts.
Serves 2 to 4.