Devil’s food cake

Heat the oven to 180C/fan 160C/gas 4 and lightly butter two deep 20cm cake tins and line the bases with baking paper.

Put the butter and chocolate into a small heatproof bowl over a pan of simmering water and heat until melted. Alternatively, put the bowl in the microwave and melt, heating on bursts of no more than 30 seconds to prevent the chocolate burning. Take the bowl from the heat and set aside.

In a large bowl, sift in the flours, baking powder, bicarb, salt and brown sugar – the sifting will help to break up any lumps in the sugar. Put the cocoa powder in a jug and pour over the hot coffee, whisking to prevent lumps. Pour the coffee mixture, buttermilk, eggs and chocolate mixture into the flour bowl, and whisk to form a smooth batter. Divide the batter evenly between the tins and bake for 25-30 minutes or until the cakes spring back to a light touch or a skewer inserted in the middles comes out clean. Allow to cool in the tins for 10 minutes before inverting onto a wire rack to cool completely.

To make the classic fudge frosting, put the butter into a large bowl and use electric beaters to beat on medium speed for 5 minutes or until very creamy. Add in the icing sugar and mix until fully combined. In a jug, mix together the cocoa powder with 5 tbsp of just-boiled water, stirring until smooth. Mix in the soured cream and then pour into the butter mixture. It may look a little curdled but don’t worry, it will come together when mixed. Scrape in the melted chocolate and beat for a few minutes until smooth and silky. Set aside to thicken slightly and then use it to frost the cake.

To make the Swiss meringue buttercream, put the sugars and egg whites into a large heatproof bowl, set over a pan of simmering water and whisk gently until the sugars have dissolved and the mixture is hot to the touch – to tell if it is finished, rub a little of the mixture between your fingers, and if there are any grains of sugar, keep heating until the mixture is smooth. Remove the bowl from the heat and use electric beaters to whisk for 7-10 minutes or until stiff peaks form and the mixture has cooled to room temperature. While this is whisking, put the cocoa powder in a small bowl and pour over 5 tbsp of just-boiled water, mixing together to form a thick paste. When the meringue is cooled, slowly add in the butter, a couple pieces at a time, whisking to combine. When the butter is combined the mixture should have formed a buttercream-like texture. Mix in the cocoa paste, vanilla and chocolate, and whisk until fully combined.

To assemble the cake, put one of the sponges onto a serving platter and top with a layer of frosting or buttercream. Put the second sponge on top and spread the remaining frosting or buttercream over the top and sides of the cake. Kept covered, the cake will keep for three to four days.