I started with roughly 200g raw unsweetened cocoa powder. To this was added 300-350ml of 95% ethyl alcohol (isopropyl could be used instead, but the alcohol must be completely evaporated). This was shaken multiple times over the course of a couple of hours, and then allowed to settle for a few days. The cocoa powder absorbed a large portion of alcohol. Only roughly 75-100ml separated.

The tincture was decanted, and then filtered. After filtration the tincture was allowed to evaporate without heating (this destroys many of the antioxidants naturally present in cocoa powder, along with any other heat sensitive compounds). You may use a fan.

After evaporation of the mother liquor a tablespoon of cocoa powder was added along with a small amount of ethanol, and then mixed thoroughly. Once completely dry, it was ground to a fine powder, and then stored away. Even though it looks light in the picture, the actual extract is much darker than what is shown in the last image below.

Note: The cocoa powder can be extracted multiple times, but three extractions should be sufficient. If you want to completely extract all the contents you may use the color of the tincture as an indicator of concentration. I extracted my cocoa three times, but I'm sure there were still some goodies/solubles left.