Mix flour & cocoa together. Cut in shortening & mix with sugar. Stir in water or milk until you have a moist cake. Place in a greased ovenproof dish. Put all remaining ingredients into a pot & stir until the cocoa & sugar is dissolved. Bring to a boil. Pour boiling sauce over the cake put straight into a 180ºC oven for 35 minutes. Remove from oven, sprinkle with white sugar & serve immediately.