Here is a goal: How to turn whiskey into irish cream?

Which way makes more sense to accomplish this goal?

Pick from:
I. Heat together half and half with condensed milk, add any flavorings your want, combine the cream mixture with whiskey in a mason jar in the fridge for a couple days, then bring to room temperature and enjoy
II. Heat together half and half with buttermilk, add any flavorings your want, combine the cream mixture with whiskey in a mason jar in the fridge for a couple weeks, then bring to room temperature and enjoy
I.