Bring the Kahlua, water and espresso powder to a boil. Add 2 tablespoons of sugar and simmer until the sugar is dissolved. Set aside.

Prepare the whipped cream–do not overwhip, you want it softly whipped. Set aside.

Beat the egg yolks, sherry and sugar in a double boiler or heat safe bowl over barely simmering water. Beat until pale and tripled in volume, about 6 minutes. Remove from the heat, and slowly beat in the mascarpone, a dollop at a time. Once the mascarpone is incorporated, fold the whipped cream in until they are combined completely.

If you are using crisp ladyfingers, dip each one completely in the Kahlua mixture, shake it off gently, and place it in the bottom of a 9 X 13 baking dish. If your ladyfingers are soft, as mine were, lay the ladyfingers out in the pan until the entire layer is covered. Brush the Kahlua mixture over the ladyfingers. Spread half of the mascarpone mixture over the ladyfingers. Repeat, ending with the rest of the mascarpone mixture. Cover with plastic wrap and chill for at least 4 hours and up to 8 hours. Sprinkle the top with cocoa powder before serving.