Using sunflower oil instead of butter gives a wonderful moist fluffiness to cakes and lets the flavour of the other ingredients do the talking. We use purple carrots, which turn the cake a beautiful deep blue colour, but, if you can’t get hold of them, regular carrots work just as well. Similarly, if it’s not blood orange season, you can use regular oranges instead. And, if you have only got one 20cm springform tin (like most normal people), just bake the cakes one after another in the same tin.

SERVES 10–12
For the cake
unsalted butter, for the tins
75g walnuts
5 eggs
250g sunflower oil
250g dark muscovado sugar
250g self-raising flour
1 tsp baking powder
1 tsp ground cinnamon
pinch of sea salt
50g raisins
50g candied mixed peel
200g carrots (2 medium), peeled and grated
For the icing
165g unsalted butter, softened
250g full-fat cream cheese, at room temperature
165g icing sugar, sifted
finely grated zest of 2 blood oranges, plus 5 tbsp blood orange juice
Preheat the oven to 155°C/fan 135°C/gas mark 3. Butter two 20cm springform cake tins and line the bases with baking parchment.
Spread the walnuts on a baking tray and toast in the oven for 20–25 minutes, or until golden brown, turning them with a spatula every 5 minutes so they cook evenly. Allow to cool, then roughly chop.
To make the cake, combine the eggs, oil and sugar in a large mixing bowl using a whisk (or in a food mixer fitted with the beater attachment), then add the flour, baking powder, cinnamon and salt. Now add the raisins, mixed peel, walnuts and carrots and mix until thoroughly combined.
Divide between the prepared tins and bake for 25–30 minutes, or until firm to touch and a skewer inserted into the middle of the cakes comes out clean. Allow to cool in the tins for 10 minutes before carefully releasing from the tins and turning out on to a wire rack. (Or bake them in the same tin, one after another.)
For the icing, ensure the butter and cream cheese are at room temperature, which will reduce the risk of any lumps forming. Beat them together in a large mixing bowl (or use a food mixer fitted with the beater attachment), then add the icing sugar and beat again until thoroughly combined. Fold in half the orange zest and all the juice.
Once the cakes are cool, spread some icing in the middle, then sandwich together and generously coat the top with the rest. Decorate by sprinkling evenly with the remaining orange zest.