Preheat the oven to 200°C/gas mark 6

To begin the cake, cream together the oil and brown sugar using a food mixer or electric beaters

Sift in the flour, salt and cinnamon. Add the eggs and stir gently until well blended

Toast the walnuts on a baking sheet in the oven, then roughly chop. Fold the finely grated carrot and chopped walnuts into the cake mixture

Turn the oven down to 160°C/gas mark 3. Spoon the cake mixture into a large, shallow baking tin and cook the cake for 30 minutes. Cool in the tin before turning out and cutting into small oblong bars

Meanwhile, to make the icing, beat the softened butter together with the cream cheese using the food mixer. Gradually add the icing sugar and beat until well blended. Chill until ready to use

Put the icing into a piping bag and pipe 3 mounds onto each piece of carrot cake