To prepare the cake
Sift together the flour, sugar, salt and bicarbonate of soda in a large mixing bowl.
Heat the butter, water, oil and cocoa in a small saucepan, stirring until it begins to boil. Immediately remove from the heat and cool slightly.
Pour the liquid into the flour mixture and mix well.
Whisk together the eggs and buttermilk and add to the batter.
Grease or spray a large ring pan or an ovenproof dish. This cake only works made in a RING pan.
Pour in the batter and bake in a preheated oven at 180°C for 30-40 minutes.
Remove from the oven and cool in the tin for 10 minutes, then turn out on a wire rack.
For the icing
Combine all the ingredients and mix until smooth, then spread over the cake.
Decorate with as desired.