Bake Play Smile
Using electric beaters (or a whisk), beat the egg yolks and sugar in the bowl over a saucepan of gently simmering water for 5-7 minutes, until it becomes pale and fluffy and increases in size.
Add the mascarpone and vanilla and continue to beat on low speed until stiff.
Place the espresso coffee and the Kahlua into a bowl and set aside to cool. Working one at a time, dip each side of the lady finger sponges into the coffee mixture and then line them along the bottom of the dish.
Once you have lined the bottom of the dish with one layer of coffee-soaked ladyfingers, add half of the mascarpone custard mixture. Then, repeat finishing off by topping with the remaining layer of mascarpone.
Cover and chill for at least 3 hours (but overnight is best!). When ready to serve, dust the top of the tiramisu with cocoa powder, using a sifter.