How to make low cal healthy hot coco?

So I've read things about using cocoa powder (unsweetened type I use for baking) on boiling water and adding whatever spices you want with. But that tastes horrible. I love dark chocolate, cinnamon and nutmeg, and hate the way a cup of milk is 80 cals. I tried alternating with 1/3 milk 2/3 water, still terrible. Any ideas?
Also tried adding vanilla extract.