For the sponge 350g/12oz dark chocolate (39 per cent cocoa solids), broken into pieces 225g/8oz butter, softened 3eggs 400g/14oz caster sugar 400g/14oz self-raising flour 1 1/2 tsps baking powder
For the truffle filling 225g/8oz dark chocolate (39 per cent cocoa solids), broken into pieces 150ml/1/4pt double cream 150g/5oz butter, softened 500g/1lb 2oz icing sugar, sifted
For the ganache icing 225g/8oz dark chocolate (39 per cent cocoa solids), broken into pieces 125ml/ 4 1/2 fl oz double cream
1. Preheat the oven to 160°C/140°C fan/gas mark 3. You will need 2 × deep 23cm/9in round loose- bottomed or springform tins, greased and base lined.
2. To make the cake, put the chocolate and butter into a pan. Add 300ml/1/2pt water and heat gently over a low heat, stirring until melted and smooth. Cool slightly.
3. Break the eggs into a mixing bowl and beat with a fork. Add the caster sugar and beat again until smooth. Gradually pour in the melted chocolate mixture and whisk by hand until smooth. Sift the flour and baking powder into the chocolate mixture and mix until smooth.
4. Divide evenly between the cake tins. Bake for 1–1 /4 hours or until springy to the touch and shrinking away from the edges of the tin. After 10 minutes turn on to a wire rack to cool and remove the paper.
5. To make the truffle filling, sit a bowl over a pan of simmering water. Add the chocolate and cream to the bowl and gently melt, stirring until smooth.
6. Remove from the heat, add the butter to the hot chocolate and cream and stir until smooth. Sift in half the icing sugar, and mix, then add the remaining icing sugar and mix until smooth. Set aside to cool until thick.
7. To make the ganache icing, gently heat the cream in a pan. Add the broken chocolate to the hot cream and stir until melted.
8. Slice each cake in half horizontally and sit one piece on a plate. Divide the truffle filling into three and spread a third of the filling on top of one cake, repeat so you have four layers of cake and three layers of filling. The side of the cake needs to be exactly level, if not trim with a serrated knife.
9. Pour the ganache icing over the top of the cake and let it run down the sides, using a palette knife to spread it evenly over the top and the sides of the cake to give a smooth shiny glaze. Set aside until firm, then cut the cake into wedges to serve.
Recipe taken from At Home by Mary Berry and Lucy Young (BBC Books). To order your copy for just £14 (usually £20) including free p&p, please call the Radio Times Bookshop on 01603 648176. (Contract with Bertrams.)