Kath,

Cocoa powder, water, stevia & dash of vanilla is excellent +
cayenne/cinnamon if you like it spicy.  If it's too watery for your tastes,
try making it with unsweetened coconut milk instead of water or 3/4 water,
1/4 coconut milk.  I've also just taken water, thrown in a tablespoon of
cocoa nibs (shelled cocoa beans) + cayenne pepper & cinnamon -- the warm
water softens the nibs (which are very crunchy)so you can mash them up a
bit -- spicy and warming and stimulating due to theobromine content -- one
caution is that this is NOT a sweet drink or anything like what we
traditionally think of as cocoa.  If you're looking for something more
along those lines -- try the recipe with coconut milk + stevia, vanilla
added.