Pour the cream and milk into a saucepan. If using a vanilla bean, add the seeds and pod.
Warm the mixture until just steaming, do not boil.
In a separate bowl, whisk together the egg yolks and sugar until lighter in color and fluffy.
Slowly add a splash of the warm cream mixture to the yolks while whisking to prevent scrambling.
Pour the egg yolk mixture back into the saucepan with the rest of the cream.
Cook gently over low heat, stirring constantly, until it thickens enough to coat the back of a spoon.
Strain the custard through a fine mesh sieve.
Let the custard cool to room temperature, then refrigerate until cold.
Churn in an ice cream maker until soft and creamy.
Transfer to a container and freeze until firm.
