1. In a mixing bowl, whisk the heavy cream until stiff peaks form.
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 coffee 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. Layer the soaked ladyfingers at the bottom of each serving cup.
7. Spoon a layer of the mascarpone mixture over the ladyfingers.
8. Repeat the layers, finishing with a layer of the mascarpone mixture.
9. Dust the top with cocoa powder.
10. Refrigerate for at least 2 hours before serving.