Method

1. Set the oven to 200°C/gas 6. Mix the breadcrumbs with 100g of the sugar, and spread out on a baking tray. Bake for 8-12 minutes, stirring at least twice until the breadcrumbs are golden and have melded with the sugar. Don't let it burn! As soon as they are done, and while still very hot, stir again, scraping up any pieces that have stuck to the tray. Keep stirring for a few minutes, until the crumbs have cooled slightly and are crisp rather than sticky. Leave to cool.

2. Put the single cream into a pan with the vanilla pod and bring up to the boil. Draw off the heat, cover and leave to infuse for 15 minutes, then bring back almost to the boil. Meanwhile, whisk the egg and yolk with the remaining sugar until pale and fluffy.

3. Whisk in the hot infused cream, then pour the mixture back into the pan. Stir over a low heat for a few minutes until the custard thickens slightly. Draw off the heat, stir in the rum and then pour into a clean bowl. Leave to cool, stirring occasionally.

4. Whisk the double cream until it just about holds its shape but is still a little sloppy, and then fold into the custard, with the breadcrumbs. Freeze in an ice-cream making machine or if you don't have one, pour the mixture into a shallow container and place in the freezer, set to its lowest setting. Leave until the sides are beginning to set, then break them up and push into the centre. Leave for another half hour or so, and repeat. Now leave until the ice cream has just about set but is not yet rock hard. Beat hard with a wooden spoon to break up all the ice crystals. Return to the freezer and leave to finish freezing.

5. Transfer from the freezer to the fridge a good 30-40 minutes before serving, to soften.