Grease and line a 24 cm (9.5 inch) springform cake pan.
In a large bowl, or the bowl of a KitchenAid, beat together the eggs, oil and sugar until it is pale and thick.
Add the flour, baking powder, salt, baking soda, ground cinnamon, nutmeg and mixed spice. Mix until well combined.
Stir through the carrots, raisins and nuts (if using). The batter will be quite liquid but don’t worry about this.
Pour the batter into the cake pan and bake for about 1 hour, or until a skewer inserted into the middle comes out clean.
Leave the cake to cool in the pan for about 5 minutes before removing it to a wire rack to cool completely.
For the Lemon Frosting
Mix together the icing sugar (powdered sugar) with just enough lemon juice to make a thick but spreadable icing.
To Decorate
Generously spread the frosting over the cooled cake.
As soon as the top of the cake is spread with icing, quickly decorate with some shop-bought marzipan carrots or chopped walnuts.
Leave the cake for an hour or so to set before serving.
Kitchen Notes
OVEN TEMPERATURES All recipes on this website state temperatures for a regular oven (i.e. a conventional oven without fan). If you have a convection oven with a fan, please consult the manufacturer's handbook on how to adjust the temperature and baking time accordingly.