Preparing the meat

Combine the yoghurt, ginger, garlic, fresh chillies (if using), ground spices (garam masala, 2 teaspoons of the turmeric, coriander, cumin, cinnamon and chilli powder) and lemon juice in a large bowl, then generously season with salt and pepper. Smother the goat shoulder in this mixture, then cover and leave to marinate in the fridge for a minimum of 6 hours or, better still, overnight.

An hour before cooking, remove the marinated goat from the fridge so it comes to room temperature. Preheat the oven to 230°c or 220°c fan. Place the shoulder in a large roasting tin and roast for 15 minutes in the preheated oven to brown in a few places. Turn the temperature down to 160°c or 150°c fan and add 250ml of boiling water to the roasting tin, then cover with a layer of baking parchment and a layer of foil, sealing tightly around the edges. Cook the shoulder in the oven for 3 hours 30 minutes.

Preparing the onions

Heat the rapeseed oil in a deep heavy-based pan over a high heat until it sizzles when a piece of onion is dropped in. Fry the finely sliced onions for 10 minutes until golden, then transfer to a plate lined with kitchen roll using a slotted spoon.

Preparing the rice

Fry the cumin seeds, cardamom pods, cinnamon stick, bay leaf and whole cloves in a saucepan with half the butter for 1 minute over a moderate heat. Add the remaining ground turmeric and the rice, then fry for another minute. Stir in 450ml of boiling water and a generous pinch of salt. Cook uncovered until the water has been absorbed (about 5 minutes).

Assembling and serving the dish

Heat the milk, then add the saffron and leave to infuse for at least 5 minutes. Meanwhile, grease an ovenproof casserole dish with butter. Layer the rice and onions in the dish with half the coriander leaves and dot with the remaining butter. Pour over the infused milk and saffron. Place the cooked goat meat on top and cover with baking parchment or foil before placing the lid on to retain as much steam as possible. Finish the biriyani in the oven for 35-45 minutes at 170°c or 160°c fan. Remove the lid and scatter the remaining coriander leaves over the top to serve.