You can use any easy muffin mix and just add some extra 250ml cocoa powder with 1 and a 1/2 cups of water.
I used the Edmonds sure to rise, sweet muffin baking mix. I just added more water than what was stated.
Bake on 190 Degrees Celsius for 30 minutes.
Makes about 18 normal size chocolate muffins.
Serve and enjoy!