Heat oven to 190˚C/170˚C Fan. Line two 7" sandwich pans with parchment and grease with butter. In a large bowl combine the dry ingredients flour, cocoa, baking powder, bicarbonate of soda and salt. Give a quick mix and set aside.

Melt together the butter and chocolate, either by giving 30 second blast in the microwave stirring between each blast until the chocolate is meted or melt in a bowl suspended over a pan of hot water.

Whisk into the melted butter and chocolate the light brown sugar, caster sugar, eggs, vanilla, and buttermilk until combined.

Pour the wet ingredients into the dry and whisk until a thick and smooth, Whisk in the hot water, pour into the prepared cake pans and bake for 35 - 40 minutes or until a skewer inserted comes out clean.

Allow to cool for 10 minutes in the tins before turning out onto a wire rack to cool completely.

Meanwhile, prepare the icing by beating the butter for a couple of minutes until pale and creamy with an electric mixer in a large bowl. (Butter must be soft, but still solid)

Sieve in the icing sugar and cocoa. mix briefly with a spatula into the butter. Add two - three spoonfuls of milk and vanilla. mix again starting off on a low speed with an electric mixer. Beat and add milk until a spreadable but thick consistency is achieved,

When Cakes have completely cooled, remove the parchment paper and place one upside down on a plate or cake stand. Dollop 1/3 of the icing on top and spread to the edge.

Place the second layer on top, again upside down. Dollop the remaining frosting on top. Spreading with an offset spatula covering the sides and top as smoothly or roughly as you like.