Pre-heat oven to gas mark 3 / 170C
Melt the butter, add the sugar and mix well.
Add the flour and cocoa and mix well until you have a stiff consistency.
Beat the egg and gently mix into the flour mixture.
Put the mixture into a greased 30cm x 18cm baking tray, and gently press into the corners and flatten into the tin.
Sprinkle with a little water and place in the top half of the oven for 45 minutes.
Then remove from oven and sprinkle with sugar.
Allow to cool for 5 mins then cut into required size pieces and place on a wire tray.
You can either eat it as it is, or make some custard to go with it for dessert.
