Tiramisu della Nonna

Directions

1. 1) Slit the vanilla pod length ways, if using, and scrape the seeds with the tip of the knife.
2. 2) Fill a pan half way with water and bring to a simmering boil. In a heat proof bowl add the egg yolks, caster sugar and vanilla seeds or extract and whisk over the slow simmering water. Whisk until thick and creamy and the mixture is ready when a trail of foam forms as you lift the whisk.
3. 3) Remove from the heat and leave to cool. Once cooled add the mascarpone and fold in the whipped cream and set aside.
4. 4) Mix the coffee with the rum and Tia Maria. Dunk the Savoiardi or sponge fingers quickly into the coffee, making sure that they are completely immersed. Note: if using sponge fingers leave in the coffee for only 1 second, or they will turn soggy. Arrange the biscuits in a single layer in a serving bowl and spoon over half the cream mixture.
5. 5) Repeat this process with another layer of dunked biscuits and another layer of cream. Sift over the cocoa powder in a even layer. Cover and refrigerate for at least 3 hours.