Combine all the ingredients (except oils) in a medium saucepan.
Whisk the mixture constantly over medium-low heat until it comes to a low boil.
Remove the mixture from heat and let it cool. Mix in the oils.
Pour the mixture into a glass container and cover it with a lid or plastic wrap. This completes your custard mixture. Chill the mixture in the refrigerator for at least two hours (or overnight).
Pour the mixture into the cylinder of your ice cream maker. For most machines, you pack the cylinder in with ice and then start the electric mixer or crank. (Check your machine’s directions, as the process might vary slightly). Let your custard mixture churn in the machine until it reaches the desired consistency.