Line 12 sections of a deep muffin tin with paper cases. Steam the pumpkin pieces above a saucepan of boiling water for five minutes until just tender.
Put all the dry ingredients (except the Demerara sugar) in a large mixing bowl. Mix the oil, milk and eggs together then add to the dry ingredients along with the yoghurt. Roughly fork the ingredients together.
Add the steamed pumpkin and raisins. Stir until just mixed then spoon into the paper cases. Sprinkle with Demerara sugar and bake in a preheated oven, 200c/gas mark 6 for 15-20 minutes until well risen and golden.