1. In a mixing bowl, whip the heavy cream until stiff peaks form. Set aside.
2. In another bowl, mix the mascarpone cheese, sugar, and vanilla extract until smooth.
3. Gently fold the whipped cream into the mascarpone mixture until well combined.
4. In a shallow dish, combine the brewed espresso and coffee liqueur (if using).
5. Dip each ladyfinger into the coffee mixture for a few seconds, ensuring they are soaked but not soggy.
6. Break the soaked ladyfingers into pieces and layer them at the bottom of the serving cups.
7. Spoon a layer of the mascarpone mixture over the ladyfingers.
8. Repeat the layers until the cups are filled, finishing with a layer of the mascarpone mixture.
9. Dust the tops with cocoa powder.
10. Refrigerate for at least 2 hours before serving.