Start by brewing 1 cup of strong coffee. Pour the coffee into a shallow bowl and let it cool completely before use to prevent the ladyfingers from becoming soggy.
In a mixing bowl, combine the mascarpone cheese and sugar. Beat until smooth and creamy. Add the vanilla extract and mix until incorporated. In a separate bowl, whip the heavy cream to soft peaks. Gently fold the whipped cream into the mascarpone mixture to keep it light and airy.
Quickly dip each ladyfinger into the cooled coffee, dipping each side for about one second to avoid sogginess. Place the dipped ladyfingers at the bottom of each serving cup to create the first layer.
Spoon or pipe a generous layer of the mascarpone cream over the ladyfingers in each cup. Smooth it out gently with a spatula or the back of a spoon.
Add another layer of dipped ladyfingers on top of the cream, then another layer of mascarpone cream. Fill the cups almost to the top, finishing with a creamy layer.
Cover the cups with plastic wrap and refrigerate for at least 4 hours, or overnight if possible, to allow the flavors to meld and the texture to set. Just before serving, dust the tops generously with unsweetened cocoa powder using a sifter or fine mesh strainer.