Separate the egg yolks and whites into two clean, dry bowls. Add 75 g of sugar to the yolks and whisk with an electric mixer until pale yellow and thickened. Add the mascarpone cheese to the yolk mixture and beat until smooth and creamy. Set aside.

In the separate bowl, whisk the egg whites until soft peaks form. Gradually add the remaining 75 g of sugar while continuing to whisk until stiff, glossy peaks form. Be careful not to overbeat.

Gently fold about one-third of the whipped egg whites into the mascarpone mixture to lighten it. Then, carefully fold in the remaining egg whites in two additions until just combined, maintaining an airy texture.

In a shallow dish, combine the brewed espresso and coffee liqueur (if using). Quickly dip each ladyfinger into the coffee mixture for about 1-2 seconds per side, ensuring they are moistened but not saturated. Arrange a single layer of soaked ladyfingers in the bottom of your serving dish or individual glasses.

Spread half of the mascarpone cream mixture evenly over the ladyfinger layer. Grate half of the dark chocolate over the cream.

Repeat with another layer of coffee-dipped ladyfingers, followed by the remaining mascarpone cream. Grate the rest of the dark chocolate over the top.

Cover the dessert and refrigerate for at least 6 hours, or preferably overnight, to allow the flavors to meld and the ladyfingers to soften.