Preheat oven to 350 degrees. Mix together cocoa and hot water in a bowl until there are no cocoa chunks in it. In a separate bowl, mix together the baking soda and baking powder, the coarse salt, and the all-purpose flour.
Put a saucepan on the stove on medium/simmering heat, and add the butter and the sugar and let it melt. Continuously mix it until it is completely melted. Turn the stove off, and mix it with a electric mixer until it cools off.