The answer to everything. This deep, dark chocolate cake is studded with raspberries that give a lovely fruity burst of flavor to cut through the sweetness.
Heat the oven to 170°C/150°C fan/325°F/Gas 3.
Place the butter and chocolate in a medium pan and cook, stirring with a wooden spoon over a low heat until melted. Add the coffee to the butter and chocolate mixture and stir together.
Place both flours, along with the cocoa, bicarbonate of soda and both sugars into a large mixing bowl. In a separate bowl, beat the eggs with the buttermilk. Then, using a wooden spoon, stir the wet ingredients into the dry ingredients, and add the chocolate mixture, mixing until smooth. Then, fold in the raspberries.
Pour the batter into the prepared tin (it should come about three quarters of the way up the tin) and bake for about 60–70 minutes, or until a skewer inserted into the sponge comes out clean. Leave to cool in the tin for 10 minutes, then turn out onto a wire rack to cool completely.
To make the ganache, place the chocolate in a small bowl. Pour the cream into a small pan and place over a low heat. Stir until almost boiling, then remove from the heat and pour over the chocolate. Leave for 5 minutes before gently stirring to make a smooth sauce. Chill the ganache for about 30 minutes, until thick enough to spread.
Spoon the ganache into the piping bag, snip the end and pipe into the ridges of the cake. Sprinkle the dried raspberry pieces on top and decorate with the pistachios and fresh raspberries.