Start by making the sugar syrup by dissolving 700g sugar into 700ml of water over low heat.
Meanwhile, slowly melt the dark chocolate (85% cocoa solids) in a double-boiler. I find that it helps to add hot syrup a little at a time to the melting chocolate so you end up with a chocolate syrup. If you add cold liquid to melted chocolate the chocolate hardens quickly into grains and it's hard to get it to melt smoothly again.
In a large bowl, whisk the cocoa powder with a little of the water until you have a thick paste. Don't add to much water or it will be hard to get the powder into a smooth paste. Once you have a nice runny chocolate syrup and the thick chocolate paste, stir the two together and add the remaining water.
Chocolate & Chile are like apple & cinnamon, so I added about 5 teaspoons of ground chipotle chile powder to the mix to get just the right balance of sweetness and heat. Different chile powders have different heat levels so it's best to add a little at a time and find some guinea pigs to test the heat.