To make the vanilla custard base, add the egg yolks and sugar to a mixing bowl, and use a hand mixer to beat them well until they triple their volume and have a pale yellow colour.
In a pan set over a medium heat, add the milk and clotted cream, and use a sharp knife to split the vanilla pod so you can scrape the seeds off - I also leave the pod in the pan until the mixture heats up to release more flavour.
Remove the warm mixture before it starts to boil, we need it warm not hot - remove the vanilla pod at this stage.
Pour it over the egg mixture, whisking well to prevent the eggs from scrambling.
Return the pan to the heat, and simmer it until it thickens and coats the back of a spoon.
Leave the mixture to cool down completely, then refrigerate it for 1-2 hours.
To make the raspberry sauce, add the raspberries to a blender, and blitz well.
Add the mixture to a pan and leave it to simmer for 5 minutes or until it reduces into a thicker sauce.
Pass the sauce through a sieve to remove the seeds, then leave it to cool down completely.
Churn the ice cream according to the manufacturer's instructions.
Transfer the ice cream to a freezer-friendly container, add the raspberry sauce, and use a teaspoon to swirl the sauce around and blend it with the ice cream.
Freeze for 3-4 hours until solid enough to scoop.