• Make espresso or very strong coffee. (5-6 Tbsp of dark roasted grounds per 3 cups of water - err on the side of making too much coffee.) Set aside to cool.
• In a double boiler, whisk together the egg yolks, salt, and sugar.
• Constantly whisking, heat over low/med heat until the mixture becomes pale yellow - about 10 minutes. A slight ribbon should fall from the whisk when lifted from the pan. (If it becomes clumpy of dry, add warm water 1 Tbsp at a time, making sure to whisk constantly so the eggs don't scramble.)
• Transfer the egg yolk mixture to a large bowl and set aside to cool.
• In another bowl, whip the cream. Set aside.
• Add the cold mascarpone and vanilla to the egg mixture and whisk together until it creates a soft, spreadable mixture and no lumps remain.
• Gently fold half of the whipped cream into the mascarpone mixture until combined. Then fold the other half of the whipped cream in.

Assembly:

• Pour the coffee into a bowl that's easy to dip the lady fingers in.
• Using a sifter, dust the bottom of an 8x8 baking dish with 1 Tbsp cocoa powder (or enough to cover the bottom).
• Working one at a time, quickly dip half of the ladyfingers into the coffee (no more than 2 seconds - they're quite porous and will fall apart if left in the liquid too long) and arrange them, rounded side up, in the bottom of the pan.
• Spread 1/2 of the mascarpone mixture evenly over the ladyfingers.
• Repeat espresso-dipped ladyfingers layer and the mascarpone layer.
• Dust with another Tbsp of cocoa powder. Top with grated chocolate.
• Cover with plastic wrap and chill for at least 4 hours (waiting 24 hours makes it even better).