Preheat the oven to 180°C.
In a bowl, mix 400 g white sugar, the flour, cocoa and baking powder. In a separate bowl beat the eggs, buttermilk.
Melt 125 g of butter and allow to cool before adding to the flour mixture. Beat for 2 minutes.
Add the vanilla and coffee, then stir.
Divide the batter between two greased 23 cm cake tins and bake for 20 to 25 minutes, or until a skewer inserted comes out clean. Allow to cool.
Heat 60 g butter, the milk and brown sugar in a saucepan and stir. Boil for 2 minutes, pour into a bowl and add half the icing sugar.
Beat for 2 minutes, then cool. Beat in the remaining icing sugar and caramel essence. Cool.
Simmer the remaining white sugar with 3 T water in a saucepan until it dissolves. Add 100 g butter and boil until it takes on a rich caramel colour.
Remove from the heat and add the cream, stirring continuously. Allow to cool.
Sandwich the two layers together with the caramel icing, then pour over the fudge sauce.
Cook's tip: you can also ice the cake with caramelised white chocolate