Make a strong espresso coffee. Pour it into a bowl or plate, add two tablespoons of sugar and let it cool to room temperature.
Separate the yolks and whites. Beat the yolks with half the sugar until fluffy and pale in color, for about 5 minutes.
Add the mascarpone and whisk it until it’s light and fluffy.
Beat the egg whites until stiff. Add the remaining sugar afterward, and continue beating for at least a minute to get a glossy, stable foam.
Add a small amount of the whites to the mascarpone cream and whisk it in. Fold in the rest gently.
Dip half of the ladyfingers one by one into the coffee mixture just enough to moisten them, and line the bottom of a container with them. I find around 2–3 seconds is the perfect dipping time.
Spread half of the cream evenly over the ladyfingers.
Optional: Sprinkle some cocoa powder over the top using a fine-mesh sieve.
Make a second layer the same way: ladyfingers dipped in coffee and the remaining tiramisu cream.
Sprinkle the top with cocoa powder. Cover with plastic wrap or a lid, making sure it does not touch the cocoa, and put it in the fridge. Let it rest for at least two hours—in my opinion, it’s even better if you make it the day before.