Lemon chocolate cake
For the topping
Preheat the oven to 180°C/350°F/Gas mark 5. Grease a 23 x 13cm/ 9 x 5in loaf tin.
Cream the butter, sugar and lemon zest together. Add the eggs and beat well. Mix in the chocolate. Sift the flour and salt together, and add to the mixture alternately with the sour cream. Beat well.
Pour the mixture into the loaf tin, and sprinkle with the icing sugar and lemon zest. Bake for 50–60 minutes until cooked. Cool on a wire rack.