crust Preheat oven to 350°F. Combine cookie crumbs, melted butter, and sugar in processor; process until crumbs are evenly moistened. Press mixture onto bottom and up sides of 9-inch-diameter tart pan with removable bottom. Bake crust until set, about 10 minutes. Cool crust completely on rack. filling Combine raspberries, 1/4 cup sugar, 2 tablespoons water, and lemon juice in processor. Puree until smooth. Pour puree through strainer set over medium bowl, pressing on solids to extract as much liquid as possible; discard seeds in strainer. Combine mascarpone, heavy whipping cream, vanilla, and remaining 1/4 cup sugar in another medium bowl. Using electric mixer, beat until mixture is smooth and stiff peaks form. Fold in raspberry puree. Spread filling evenly in cooled chocolate crust. Cover and refrigerate tart overnight. topping Arrange fresh raspberries in concentric circles atop tart. Stir raspberry preserves in heavy small saucepan over medium-low heat until melted to form glaze. Brush glaze over fresh raspberries. Refrigerate tart at least 1 hour and up to 4 hours. Remove tart pan sides. Place tart on platter. Cut into wedges and serve. To make the crumbs for the crust, finely grind purchased plain chocolate wafer cookies in a processor.