Make the coffee and allow it to cool down in a bowl, waiting for it to reach a temperature of about 40°C.
Whip the egg yolks with the sugar
Then gradually add the mascarpone a little at a time, thus obtaining a soft cream.
Soak 30 savoiardi in the coffee, one by one, facing the sugar side to the coffee, being careful not to steep them excessively, then arrange them in a row in the center of a circular plate. (Place them very close, sugar side up, to create a good consistency).
Spread half of the mascarpone cream on the savoiardi and then add another layer of 30 savoiardi dipped in coffee, and spread the surface with the remaining mascarpone cream.
Cook the tiramisu in the fridge for at least 24h. This is the minimum to even be able to call it tiramisu. Otherwise it is under-proofed and the flavours do not blend.
Sprinkle with sifted bitter cocoa and serve in wedges.
