Pre-heat your oven to gas mark 3.
First, begin by placing the whole orange for the icing in a pan of hot water.
Put the pan on a medium heat and bring to a rolling boil.
The orange will need to boil for roughly 1.5hrs or until the skin is soft and the fruit is bouncy to the touch.
Whilst the orange is boiling add the fruit and peel to the citrus juices in a bowl, and place to one side.
Next separate the whites from the yolks.
In a large bowl whisk the yolks with the sugar and then slowly add the oil a little at a time until it has become thicker and airy.
Stir in the fruit along with the peel and any juices left in the bowl before adding in the carrots.
Ensure the fruit and vegetables are well combined with the sugar and egg mix before stirring in the flour and spices slowly. The mix will get quite stiff so it is easier to do this gradually.
In a separate bowl, whisk the remaining egg whites to soft peaks before gently folding these into the floury cake mix.
Spoon into a lined loaf tin and cook for 1 – 1.5hours at gas mark 3 or until the cake is bouncy to the touch and a skewer comes out clean.
When the cake is done, turn out onto a cooling rack and allow to cool completely before beginning the icing.