Chocolate Carrot Cake

Ingredients:

For The Sponge:
3 large free-range eggs
175g caster sugar
200ml sunflower oil
250g finely grated carrots (about 5 medium)
200g plain flour
3tbsp cocoa powder
1tbsp baking powder
1tsp ground cinnamon
1tsp ground ginger
125g walnut pieces or chopped pecans
For The Filling and Topping:
100g unsalted butter, very soft
100g of good-quality cream cheese
½tsp vanilla essence
300g icing sugar, sifted
5tbsp cocoa powder sifted
2tbsp walnut pieces or chopped pecans to decorate
2 x 20.5cm sandwich tins, greased and base-lined