175g unsalted butter, softened, plus more for the tin
100g chocolate (50-60% cocoa), finely chopped
200g plain flour
1 tsp baking powder
1 tsp bicarbonate of soda
100g ground almonds
275g dark muscovado sugar
1 tsp vanilla extract
3 eggs, lightly beaten
150ml buttermilk
For the fudge icing
90g chocolate (50-60% cocoa), broken into pieces
40g unsalted butter, softened and diced
1 tbsp golden syrup
2 tbsp dark muscovado sugar
150ml double cream
1. Preheat the oven to 180ºC/fan 170ºC/350ºF/gas mark 4. Butter 2 x 20cm round sandwich tins, each 4.5cm deep, and line the bases with baking parchment.
2. Place the chocolate in a bowl and pour over 120ml just-boiled water. Stir until melted, then set aside to cool.
3. In a bowl, sift together the flour, baking powder and bicarbonate of soda, then stir in the ground almonds. In the bowl of an electric mixer (or in a bowl with an electric hand whisk), cream together the butter and sugar until very light and fluffy (this will take a good 5 minutes). Add the vanilla extract to the eggs. With the whisk running, very slowly add the egg mixture to the butter and sugar, adding 1 tbsp of the flour during the process to prevent curdling, then add the melted chocolate and the buttermilk.
4. Fold in the remaining flour very gently and divide the mixture between the tins. Bake for 30-35 minutes, or until firm to the touch. Leave for a minute or 2 in the tins before turning out on to a wire rack. Remove the papers and leave until absolutely cold.
5. To make the icing, melt the chocolate and butter in a bowl suspended over gently simmering water. Make sure the base of the bowl does not touch the water. Remove the bowl from the heat, then stir in the syrup and sugar and, lastly, gradually pour in the cream until all is well blended and smooth. Allow to cool completely, then whisk until it thickens. Spread half on the base of 1 cake. Sandwich the 2 cakes, bases together, then spread the remaining icing on top.