Heat the heavy cream in a saucepan until it just begins to simmer. Remove from heat and pour over the chopped dark chocolate. Let sit for a minute, then stir until smooth. Set aside to cool slightly.

In a mixing bowl, beat the mascarpone cheese, powdered sugar, vanilla extract, cocoa powder, and melted dark chocolate until smooth. In a separate bowl, whip the heavy cream to stiff peaks, then gently fold it into the mascarpone mixture.

Mix the brewed coffee and coffee liqueur in a shallow dish. Quickly dip each ladyfinger into the mixture for about 1 second per side (do not oversoak).

Spread a thin layer of chocolate ganache at the bottom of your baking dish. Arrange a layer of soaked ladyfingers over the ganache. Spread half of the mascarpone mixture over the ladyfingers, followed by another layer of chocolate ganache. Repeat with another layer of soaked ladyfingers, the remaining mascarpone mixture, and a final dusting of cocoa powder.

Cover and refrigerate for at least 4 hours (preferably overnight). Before serving, sprinkle with dark chocolate shavings.