Using root vegetables in baking isn’t new. Carrots and parsnips are some of my favourites to play around with, but sweet potato has its place, too. It brings such a pleasant squidginess and earthy flavour that just sings autumn. Roast the potatoes in their skins, then scoop out the flesh or, for something quicker, just stick them in the microwave; I’d avoid boiling them, though, because that introduces too much extra water. This is a proper cosy cake, one that requires a good tea in your biggest mug. Sweet potato ginger cake Prep 15 min Cook 1 hr Serves 10-12 120ml neutral oil 2 eggs 150g light brown sugar 80g caster sugar 20g treacle 250g cooked sweet potatoes, mashed 30ml milk 220g plain flour 1½ tsp baking powder ¼ tsp bicarbonate of soda 1½ tbsp ground ginger A pinch of salt 1 tbsp finely chopped stem ginger For the cream cheese frosting 100g unsalted butter, softened 150g icing sugar 100g cream cheese, softened 1 tbsp stem ginger syrup Crystallised ginger, to decorate Heat the oven to 180C (160C fan)/350F/gas 4, and grease and line a 20cm cake tin. Put the oil, eggs, both sugars and the treacle in a bowl, mix to combine, then stir in the mashed sweet potato and milk. In a second bowl, sift the flour, baking powder, bicarb, ground ginger and salt, then tip into the sweet potato mix, stir to combine, then fold in the chopped stem ginger. Pour the batter into the prepared tin, then bake for 45-50 minutes, until a skewer inserted into the centre comes out clean. Remove from the oven and leave to cool completely. Meanwhile, make the frosting. Beat the butter and icing sugar until smooth and creamy, then beat in the cream cheese. Stir in the stem ginger syrup, then spoon the icing on top of the cooled cake, decorate with crystallised ginger, slice and serve.