Stir together all ingredients in a resealable jar or bowl.
Cover and refrigerate overnight.
Stir before serving and add additional milk (for a thinner consistency) and agave nectar if desired.
Prep time doesn't include time spent overnight in fridge. You can substitute any kind of milk for the almond milk, but you may need to adjust the amount of agave nectar you use. If you don't keep agave nectar on hand, brown sugar or honey would both work well in this recipe.