If using cold brew coffee, warm up the coffee and add sweetened condensed coconut milk. That way it mixes into coffee. If using freshly brewed coffee, add sweetened condensed coconut milk and mix well. Pour into a mason jar.
Add rolled oats and cardamom. Let sit a few minutes and enjoy (since it's hot), or let cool and place in the fridge and let sit overnight.
Top with coconut chips or flakes, chocolate chips, or nuts.
Video
Notes
These Thai overnight oats will last up to 3 days in the fridge.