Tiramisu ice-cream cake

1. Put the milk in a saucepan with the vanilla bean and seeds. Heat over low-medium heat until the milk is just about to boil. Remove from the heat. Remove the vanilla bean.

2. Whisk the egg yolks and sugar until pale and frothy. Whisk in 60ml (1/4 cup) of the hot milk mixture until smooth. Whisk in the remaining milk mixture, then return to a clean saucepan and stir constantly over low-medium heat for 8-10 minutes, or until the mixture thickens and coats the back of the spoon. Do not allow the mixture to boil.

3. Strain the custard and divide between two freezer-proof bowls. Dissolve half the coffee granules in one bowl, and stir the marsala into the other. Refrigerate both bowls of custard for 30 minutes, or until cold.

4. Combine the remaining coffee granules in a small bowl with the liqueur and 125ml (1/2 cup) of boiling water. Refrigerate until required.

5. Whip the cream until soft peaks form. Fold half the cream through the coffee custard, and half through the marsala custard. Transfer the bowls to the freezer. When the ice-cream starts to set, whisk well to break up the ice crystals. Freeze until the ice-cream is firm, then beat well again.

6. Line the base and the two long sides of a 17cm × 8cm × 10 cm loaf tin with foil and brush with water.

7. Spoon the coffee ice-cream into the tin, levelling the surface. Dip both sides of the savoiardi in the chilled coffee liqueur mixture and arrange over the coffee ice-cream in a tight layer, trimming to fit and gently pressing them down. Spoon the marsala ice-cream over the top and level the surface. Cover the tin with foil and freeze until set. Lift out of the tin, remove the foil and cut into slices to serve.

Alternatively, to prepare the ice-cream in an ice-cream machine, churn the coffee custard until partly set, then spoon into the tin, top with the coffee-soaked savoiardi and freeze while you churn the marsala custard.