• Heat the oven to 180C/160C fan/gas 4. Oil the base and sides of the cake tin.
• Weigh the sugar into a mixing bowl and break up any lumps before adding other ingredients. Add sunflower oil and eggs. Lightly mix with a wooden spoon or bakers whisk. Stir in the grated carrots.
• Sift the flour, bicarbonate of soda, spices into the bowl. Mix everything together, the mixture will be a soft batter.
• Pour the mixture equally into the prepared tins and bake for 40-45 mins. Test by inserting a skewer which should come out clean.
• Cool in the tin for 5 or 10 minutes then push out the cake on the bases. Carefully run a palette knife between the cake and the base to remove the bases. Cool on a wire rack.

Topping

• Mix the butter icing as in the recipe below. You will use about two thirds of the icing.
• Choose the cake which has risen with the lowest domed surface and turn upside down. Using a palette knife apply the icing evenly over the flat surface, ensuring that the outer edges are covered. Thickness should be about 3mm allover.
• Sit the 2nd half on top and similarly apply the butter icing. Finish with moving the knife in circles around the surface to make it as smooth as possible
• Zest the orange evenly spaced over the surface.

• Put the butter, vanilla extract, two tablespoons of the milk, and half the icing sugar in a large bowl and beat until smooth. Beat in the remaining icing sugar, and pour in the rest of the milk if needed to make the icing the right consistency.