Combine cream, sugar, vanilla extract, blackberry liqueur, cocoa powder, and mascarpone in a large bowl. Using an electric mixer on medium speed, beat until firm peaks form. Set aside.
In the bottom of a 9-inch springform pan (or on a 9-inch platter), arrange 12 cookies in a circle to form a base. Spread about 1/3 cup of the whipped cream mixture evenly to cover. Repeat layering the cookies and cream until all the cookies are used; top with remaining cream mixture. Cover tightly with plastic wrap and refrigerate for 5 hours or overnight.
Note: Cover the cake well before putting it in the refrigerator to set so that it doesn’t take on any odors in your fridge.
Beverage Pairing:Convento Cappuccini Brachetto d’Acqui, Italy. The best way to pair wine with this ultra-rich dessert is to contrast it with something light and effervescent. Brachetto d’Acqui is such a wine. Red and sparkling, it has the sweetness to pair with the dessert, but the buoyancy and delicacy to leaven the heavy chocolate and mascarpone.