Put all ingredients in a medium pot. You don't want a small pot as you don't want the milk to cook over. Coconut milk foams just like regular milk, maybe even more so.
Stir to combine in the pot, and then turn on the stove to medium heat (not high heat!)
Keep an eye on this. The second the milk starts to boil, reduce the heat to your lowest setting. You want a VERY gentle simmer, if that.
Skim the foam off the top.
Cook for about 1 to 1 1/2 hours, stirring every 10 minutes or so and skimming the foam off the top as needed.
After about an hour or so, you will notice that the mixture has greatly reduced and gotten considerably darker and thicker. At this point, you can turn it off.
Allow to cool for a bit and then transfer to a glass jar.
Chill overnight in the fridge. (It will thicken as it cools)