Brew a good, strong coffee and let it cool. A good tip is to put the coffee in the freezer, so it cools faster.

Once the coffee is cooled, pour in the Kahlua.

Separate the eggs into whites and yolks. Beat the egg yolks together with the sugar and vanilla seeds until you get a fluffy eggnog. You will need to beat hard and long, and the mixture should foam a lot.

Then, stir in the mascarpone.

In another bowl, beat the egg whites into a fine foam (the bowl should be able to be turned upside down). Gently fold the egg whites into the eggnog with a spatula – be careful not to knock the air out of the mixture.

Find a suitable, long-shaped dish (e.g., a baking dish/bread pan) and dip one end of the cookie in the coffee/alcohol mixture. 

Let the cookies cover the entire bottom and add a layer of cream over them.  Repeat the process with another layer of cookies and cream. 

Let the tiramisu sit in the fridge overnight. Or make it in the morning to ensure it rests for at least 4-6 hours before serving.

When serving, sift the cocoa powder through a small sieve. It's a good idea to hold the sieve 30-40 centimeters above the dish so it spreads in a fine layer.

Cut the cake into appropriate pieces and serve.