Prepare the coffee and let it cool in the fridge.
Meanwhile, in a bowl separate the white from the yolk of the eggs, and assemble the whites to the point of snow. It can be made by hand, or more easily by making use of an electric rod mixer.
In another bowl, assemble the yolks together with the sugar until it is dissolved completely and the mixture increases in size and adopts a more yellow tone.
Then, add the mascarpone cheese little by little until you get a lump-free and soft dough.
Add the egg whites that we had reserved and mix again gently until we get a mixture with all the ingredients perfectly integrated. It is important that the creamy texture that has been achieved by mounting the whites to the point of snow is maintained.
In a rectangular mold, cover the base with ladyfinger biscuits and wet them with cold coffee. Distribute a third of the mixture of mascarpone cheese and eggs on top of the biscuits until completely covered.
Repeat the previous step two more times, until we have assembled a total of three layers of biscuits, coffee and cream.
We reserve and keep the result in the fridge for a minimum of 4 hours, until the time of serving. Although it is highly recommended that we let it rest for about 8 hours. This way, we allow the flavors to settle and the cream to acquire more consistency.
Finally, before serving, sprinkle the fstk cocoa powder, sifting with a strainer, until covering the tiramisú with a thin layer.