Carrot cake cupcakes with cream cheese frosting

Name: Carrot cake cupcakes with cream cheese frosting
Ingredients: 275g/9¾oz caster sugar; 200ml/7fl oz sunflower oil; 4 medium free-range eggs; About 300g/10½oz grated carrot, a little more or less is fine; Up to 150g/5½oz nuts or dried fruit (optional); 225g/8oz spelt or wholemeal flour; 2 tsp baking powder; 1 tsp ground cinnamon; 1 tsp mixed spice; 1 tbsp cocoa powder; 125g/4½oz unsalted butter, softened; 125g/4½oz full-fat cream cheese; 275g/9¾oz icing sugar; Edible decorations (such as sugar-paste carrots or mini-chocolate easter eggs), to finish