Carrot patch cake

Name: Carrot patch cake
Ingredients: 175ml vegetable oil plus extra for the tin; 75g natural yogurt; 3 large eggs; 1 tsp vanilla extract; 200g self-raising flour; 250g light muscovado sugar; 2 tsp ground cinnamon; ¼ fresh nutmeg finely grated; 200g carrots (about three), grated; 100g sultanas or raisins; 100g pistachios finely chopped (or slivered if you can get them); 100g slightly salted butter softened; 200g icing sugar; 100g full-fat cream cheese; 100g fondant icing or marzipan; orange food colouring