In a mixing bowl, whip the heavy cream until soft peaks form.
In another bowl, blend the mascarpone, sugar, and vanilla until smooth.
Gently fold the whipped cream into the mascarpone mixture.
Dip ladyfinger halves quickly in coffee and layer them at the bottom of each dessert cup.
Spoon a layer of the mascarpone cream on top.
Repeat with another dipped ladyfinger layer, then another layer of cream.
Dust the tops generously with cocoa powder.
Chill in the fridge for at least 1 hour before serving—if you can wait that long.