In a large saucepan, add the butter, dark chocolate, caster sugar and water.

Stir on low heat until combined and then set aside for 10 minutes to cool.

Combine plain flour, self raising flour and cocoa in a large mixing bowl.

Add the liquid to the flour and cocoa mix.

Add the eggs and beat together until combined. Make sure there are no lumps of flour.

Pour mixture into a greased tin and cook for an hour on 160 degrees Celcius. Keep an eye on the cake as times vary depending on your oven.

Once cooled, ice as desired.