Place 2 cups Heavy cream, 1 cup Whole milk, and vanilla (1 tsp Vanilla extract or 1 Vanilla bean) into a medium heavy-based saucepan. Heat until mixture just starts to simmer.
Meanwhile beat 5 Egg yolks and ½ cup Sugar in a bowl until pale and thick.
Slowly whisk half of the cream mixture into the egg mixture (after removing the vanilla bean, if used). Then pour back into saucepan.
(optional) Add ½ cup Creamy peanut butter.
Return mixture back to low heat. Stir constantly with a wooden spoon until mixture as thickened and coats the back of the spoon.
Pour mixture into a heatproof bowl, cover, and refrigerate until well chilled.
Pour chilled mixture into ice cream bowl. Set ice cream maker to ICE CREAM and churn.
(optional) Add 12 Oreos when the machine specifies to add mix-ins.
Once mixture is frozen transfer to a freezer-safe container and freeze for up to one week.
