Preheat oven to 160°C \ 320°F . Grease and line with baking paper a cake tin .
Combine the chocolate and butter in a heat proof bowl over pot of simmering water and stir over low until both have melted together .
Sift flours together with the cocoa powder and mix to combine , add the brown sugar and mix to combine all then make a well in the center of the flour mix and add the oil and the melted chocolate mixture and mix with a spoon to just combined then add the eggs and mix mix well to combine all but making sure not to over beat the mixture .
Pour cake mixture into the prepared cake tin and even out . Place in Preheated oven and bake for 2 hours or until a skewer comes out clean when inserted into center of the cake , leave cake in cake tin till cake cools then turn onto a wire rack to cool completely .
once cooled dust with extra coca powder and serve with fresh fruit , cream , ice cream , topping of your choice or just as good on it's own . enjoy . :-) .