I use a slightly modified version of Rogue's recipe. I changed it due to what I had on hand at the time. I also went with 8oz cocoa powder in the boil as opposed to using an extract in the secondary as I tend not to like extracts...
I did it last year for the first time and found it lacked a 'chocolate' flavor.
This year I did it and added 8oz lactose (non-fermentable sugar) in the boil. Well, at bottling, it wasn't sweet enough so, I added another 8oz and bottled it up. I let them set for about a week before touching them and they turned out fantastic! Without the sugar component, your cocoa is just cocoa, not chocolate...
Here is the recipe I used, taken from the stickies in my garage...
11# two-row
.5# crystal malt
.5# chocolate malt
.5# caramel malt
.5# oats
I followed their hops and mash schedule.
I added 8oz lactose at the last 20 minutes of the boil.
I added 8oz cocoa powder at the last 20 minutes of the boil.
When I transferred to primary, I did so through a strainer, which is a PITA to be honest, the powder clogs it up something fierce.
When I transferred to secondary, I used glycerin to aid in clearing the beer. Truth be told, I'm not sure how much this step really matters as it is a stout. They're supposed to be thick and black. I was actually a little disappointed that I could 'almost' see through mine...
Next time, I'm going to just primary and leave alone.
At bottling, I added 3/4 priming sugar and another 8oz of lactose.