First make the gravy.

Melt the ghee in a large, heavy-based saucepan on a medium heat, add the cumin seeds, bay leaves and cloves, and fry for a few seconds.

Stir in the sliced onion and cook, stirring often, for 30-35 minutes, until softened.

When the onions start to brown, transfer half of them to a plate and set aside (you’ll use them later during the layering).

Add the green chillies and ginger to the remaining onions in the pan, fry for a minute, then stir in the tomato puree, chilli powder, turmeric and coriander powder, and fry for a minute.

Turn down to a low heat, stir in the yoghurt and cook for two minutes.

Add the squash and mushrooms, stir to coat in the spices, then fry for three minutes.

Add the stock or water, and season to taste.

Bring to a boil, then turn down the heat, cover and simmer for 18-20 minutes, stirring once halfway to make sure nothing’s stuck to the bottom of the pan.

Garnish with coriander, then take off the heat.

Heat the oven to 200C (180C fan)/390F/gas 6.

Wash the rice, then put it in a saucepan with a litre of water and the bay leaves, cardamom and salt.

Bring to a boil, cook for 10-12 minutes, until three-quarters cooked, then drain.

To build the biryani, put a tablespoon of melted ghee in a casserole pot for which you have a tight-fitting lid.

Ladle in half the vegetable curry, then top that with half the rice.

Add half the saffron water, ginger, mint, ground cardamom and garam masala, then add the reserved fried onions.

Top with the remaining vegetable curry, then spoon on the remaining rice.

Top with the remaining ghee, saffron water, ginger, mint, ground cardamom and garam masala.

Cover with baking paper, cover with the lid, then bake on the middle shelf of the oven for 15-17 minutes, so all the flavours soak into the rice.

Take out of the oven, leave to rest, still covered, for 10 minutes, then lift off the lid and serve with raita and salad.