Whisk egg yolks and sugar in a small bowl until pale, set aside.
Heat the cream and milk in a large saucepan until simmering, then remove from the heat.
Slowly pour one cup of milk into the yolks while whisking as quickly as possible. Stir yolks back into the saucepan of milk.
Continue heating the custard on a medium heat until it thickens and coats the back of a spoon. Remove from heat.
Stir through vanilla, then transfer to an airtight container. Chill for at least 3 hours, but preferably overnight.
Following the manufacturer's instructions, churn the custard base in an ice cream machine. When the ice cream is almost complete, toss in the Oreo crumble. Don't add them too early; it will give the ice cream a grainy texture.
Freeze for at least 3 hours until hardened.
