I've re-worked this stout recipe and it came out much better in version 2.0. I have a few more tweaks due to an upgrade in equipment and will brew version 3.0 in 2014. The second version sat in the primary much longer than my usual beers (Four months) but still had cocoa powder issues. It still leaves cocoa streaks in the bottom of a serving glass and has virtually no head whatsoever. What this thread has taught me:
Mint flavor fades fast: Using the natural mint found in mint tea bags fades fast. In the first batch, I used extract at bottling and that did well, but it tasted a little bit more like a mint candy than a natural mint flavor. This second batch used natural mint from mint tea and tasted fine on brew day, but the flavor faded very quickly as was barely discernible at bottling. I had to bump it up again, with a very careful extract addition.
Fats are the enemy of head retention: Using cocoa powder introduces a lot more to the beer than just chocolate flavoring. There's a lot of oil and fat in it as well, and it just murders the head. Version 3.0 will use cacao nibs or more chocolate malt instead of cocoa powder.
Cocoa powder is impossible to rack off: No matter how long it sits in the primary, you can't get rid of all of the cocoa powder residue without filtering this beer. I let version 2.0 sit in the primary for FOUR MONTHS and still had plenty of suspended cocoa in the beer.