Preheat the oven to 190C/Gas5; grease and line a springform 20cm tin with baking paper;
Whisk the oil and caster in a large bowl, then whisk in the egg yolks and milk and fold in the carrot, walnuts and raisins;
Combine the polenta and ground almonds in a bowl, then sift in the baking powder and stir in the spices; stir into the carrot mixture
Whisk the egg whites in another bowl until they are stiff and fold them into the cake mixture in two batches;
Transfer the mixture to the cake tin and bake for 30-35 minutes until shrinking from the sides and a skewer inserted into the centre comes out clean;
Run a knife around the top edge of the cake, which will be very delicate and leave it to cool in the tin
Just before serving, spoon the yogurt over the cake.
Mix together the icing sugar and extra cinnamon, then dust over the cake and scatter over some dried cranberries if you wish