Heat the oil in a large saucepan and cook the pumpkin until it is golden – even caramelised in places – then remove the pieces with a slotted spoon and set aside.
Add the onion to the pan and cook until soft and pale gold. Add the turmeric and cook for another minute.
Tip in the rice and stir it round in the fat and onion for a couple of minutes. Put the pumpkin back into the pan along with the bay leaves, cinnamon, dried fruit, chestnuts and orange zest.
Pour in the stock and season well. Bring to the boil and boil hard for two minutes, leaving the pan uncovered. There should be just a little liquid still on top of the rice.
Wrap the lid in a tea towel and put it on the pan, making sure that none of the cloth is hanging over that could catch on the flame. Turn the heat down low and leave to cook for 15 minutes. The rice should be perfectly cooked. Fork it through, adding the fresh herbs. Check the seasoning.
Heat the butter in a saucepan or frying pan and quickly sauté the chillies (they just need a minute). Serve the plov topped with yogurt, and pour spiced butter over each portion.