In a large mixing bowl, beat the egg yolks and sugar on high speed for 15 to 20 minutes until the mixture becomes pale, thick, and creamy. The sugar should be fully dissolved, and the consistency should resemble a smooth custard.

Gradually add the mascarpone cheese, folding it gently with a spatula or mixing on low speed until fully incorporated. The mixture should be rich and silky without lumps.

Evenly spread a thin layer of mascarpone cream on the bottom of the serving dish. This helps prevent the coffee from seeping to the edges.

Pour the cooled espresso into a shallow dish. Quickly dip each ladyfinger into the coffee for about one second per side, ensuring they absorb some liquid but do not become soggy. Arrange them in a single layer over the mascarpone cream.

Spread half of the remaining mascarpone cream evenly over the layer of ladyfingers, making sure to cover them completely. Smooth the surface gently with a spatula.

Dip the remaining ladyfingers in espresso and arrange them on top of the mascarpone layer. Finish by spreading the rest of the mascarpone cream evenly over the top, smoothing it out for a clean finish.

Cover the dish with plastic wrap and refrigerate for at least six hours, ideally overnight, to allow the flavors to meld and the tiramisu to set properly.

Before serving, dust the top generously with unsweetened cocoa powder using a fine sieve. Serve chilled and enjoy the authentic taste of Italian tiramisu.