In a large bowl, whisk the eggs yolks and sugar for 5 minutes, until mixture is thick and pale yellow in color. Then add the mascarpone cheese and 1 tablespoon of the espresso, and beat until smooth.
In a shallow bowl, mix the remaining espresso with the vanilla essence, and dip each ladyfinger for a couple of seconds on each side. The key is not letting the ladyfingers soak too long because it will fall apart, and make the final product too soggy.
Place ladyfingers on the bottom of a medium sized shallow dish. Then evenly spread half of the mascarpone mixture over the ladyfingers and dust with cocoa powder. Add another layer of the soaked ladyfingers and add the remaining mascarpone mixture on top.
Cover the tiramisu dish with cling film and chill for a minimum of 2 hours. Dust with the remaining cocoa powder before serving.