Combine egg yolks and sugar in a medium-sized bowl and whisk until pale in colour. Set aside.
In a medium saucepan, heat milk and cream on a medium-high heat until simmering, then remove from heat.
Pour one cup of the heated dairy into the yolks while whisking until combined. Stir in the cinnamon and vanilla.
Whisk the yolks back into the saucepan of milk and resume cooking on a medium heat until the mixture thickens and coats the back of a spoon. Do not allow it to boil.
Give the custard base time to cool a little, then pour it into a container. Refrigerate for at least 2 hours until completely cooled.
Scoop the mixture into an ice cream maker and churn, following the manufacturer's instructions. Transfer to an airtight container and freeze for at least three hours or until hard.
