Brew the espresso and let it cool slightly. Dip the ladyfingers in the coffee, one at a time, and arrange them at the bottom of your serving dish.
Separate the egg yolks from the whites.
In a mixing bowl, whisk together 50 g (¼ cup) of sugar and the egg yolks until the mixture becomes pale and creamy (this is called "ribbon stage"). Add the mascarpone and mix until smooth.
In another bowl, beat the egg whites with the remaining 50 g (¼ cup) of sugar until stiff peaks form. Gently fold a small portion of the beaten egg whites into the mascarpone mixture with a whisk. Then, carefully fold in the rest using a spatula to maintain the airy texture.
Pour half of the mascarpone cream over the ladyfingers in the dish. Add another layer of coffee-dipped ladyfingers, followed by the remaining mascarpone cream.
Cover and refrigerate overnight for the best results (at least 2 hours if you’re short on time).
Before serving, dust generously with cocoa powder.