Soak raisins in rum overnight, or warm with 1 cup rum over low heat until plump. Cool before use.

Whisk sugar and egg yolks until pale and creamy.

Heat milk and cream until just below simmering.

Temper yolk mixture by whisking in warm milk a little at a time, then return all to the pot. Add salt and vanilla.

Cook custard until it coats the back of a spoon.

Strain into a bowl and chill for at least 2 hours.

Add custard to ice cream maker per machine instructions and churn, adding soaked raisins near the end.

Serve soft-serve, or transfer to a container and freeze 1–2 hours for firmer scoops.