In a large mixing bowl, whip the heavy cream until soft peaks form. Gradually add the powdered sugar and vanilla extract, continuing to whip until stiff peaks form.

Gently fold in the mascarpone cheese until fully combined and smooth. Be careful not to deflate the whipped cream.

In a shallow dish, combine the cooled coffee and coffee liqueur, if using. Dip each ladyfinger into the coffee mixture for about 1-2 seconds, ensuring they are soaked but not soggy.

In a 9x9-inch square dish, layer half of the soaked ladyfingers on the bottom. Spread half of the mascarpone mixture over the ladyfingers.

Repeat the layering process with the remaining ladyfingers and mascarpone mixture.

Cover the dish with plastic wrap and refrigerate for at least 4 hours, or overnight for best results.

Before serving, dust the top with cocoa powder and garnish with dark chocolate shavings, if desired.