When I worked with cocoa powder (probably Dutch process), I put it in the carboy and then racked onto it, leaving half a gallon of headspace for any shenanigans it wanted to get up to (it really didn't, though). I found that until I backsweetened it, it smelled like cocoa, but you couldn't taste the chocolate, unsweetened all it contributed was bitterness. Once I backsweetened it though, I was really happy with it. I let it sit long enough that it had all settled to the bottom so I could rack off the very thick layer without too much trouble. I did add bentonite to clarify it and it worked quite well.