Preheat the oven to 180 degrees Celsius. Line a 23cm round spring from tin with baking parchment
Beat the eggs and the oil together with the sugar. If using coconut oil and it is solid, melt it gently first.
Sift the flour and other dry ingredients together and fold into the egg mixture until well blended.
Stir in the walnuts if using and the grated carrots.
Pour into prepared cake tin and place in the oven. Cook at 180 degrees for 30 minutes then reduce the heat to 150 degrees Celsius and cook for a further 20 to 30 minutes or until a skewer inserted into the centre of the cake comes out clean.
Remove form the oven when done and leave to cool in the tin.
Once cool, tip out of the tin.
To make the icing, beat the cream cheese with the butter, icing sugar and orange zest.
Spread over the top of the cake. Garnish with more walnuts or mini decorative carrots* and a few gratings of orange zest.