Cocoa powder = dark chocolate bars?

um, well, there are antioxidants in chocolate and in cocoa, so if that's what you mean by "healthy," then you are getting them from both sources. I have no idea how much of the relevant flavenols are in a tbsp of cocoa, or in, say, an ounce of 85% dark chocolate either. As far as I know, a U.S. RDA for chocolate has not yet been established. However, I do recall that there was some evidence that something in milk that interferes with the absorption of the antioxidants from the chocolate, which led to the conclusion by those researchers that dark chocolate was "healhier" than milk chocolate. So if you put milk in your coffee, that might counteract the antioxidant effect. Assuming there was one to begin with. On the other hand, the whole coffee-cocoa-milk combination would be one heck of a lovely way to kick off a day. I think I'll have some tomorrow.

Cocoa powder
http://www.sciencedirect.com/science/article/pii/S093947531100038X

Consumption of cocoa power with milk modulates the lipid profile in high-risk subjects for CHD. In addition, the relationship observed between the urinary excretion of cocoa polyphenol metabolites and plasma HDLc and oxLDL levels suggests a beneficial role for cocoa polyphenols in lipid metabolism.

I make my own chocolate with butter, sweetener, flour and cocoa powder. Still experimenting with the ratio though. You could probably get a recipe online.