Whip the egg yolks with the sugar and water over a water bath, while stirring, until creamy. About 10 minutes until the sugar has also dissolved. The best way to do this is to use a whisk. Remove the bowl from the water bath and transfer the ice cream to a fresh mixing bowl. Beat again with the mixer for a few minutes and allow to cool.
There you add the mascarpone and stir it in.
Whip the cream until stiff and stir into the cream.
Line a rectangular 34 × 24 cm baking dish with a layer of ladyfingers. Drizzle half of the coffee liqueur over the biscuits. Then spread half of the cream on top and smooth it out. Cover with another layer of ladyfingers and drizzle with the rest of the coffee liqueur. Spread the rest of the cream on top and smooth it out. Now dust the top with cocoa powder and sprinkle the grated chocolate on top. Place in the refrigerator for at least 3 hours, or overnight.