Line your muffin tin with paper cases. Preheat oven to 190C/Gas 5 Zest the lemon and keep to one side Grate the courgettes and apple into a bowl. Add the juice of the lemon, the egg and oil and mix together. Add the flour, baking powder, sugar and cinnamon and combine well. It doesn’t matter if the mixture is lumpy. It makes for a lighter muffin in the end. Add the sultanas and stir to combine. Spoon the mixture into your 12 paper cases and cook in the preheated oven for 25 minutes. After 25 minutes check they are done. If a skewer comes out clean they are fine. If not put back in the oven for a further 5 minutes. Cool completely in the tin. Ice with the cream cheese mixture and sprinkle with lemon zest.