Marinate the Chicken: In a large mixing bowl, combine the chicken pieces with all the marinade ingredients: natural yoghurt, ginger-garlic paste, turmeric, chilli powder, ground coriander, garam masala, lemon juice, and salt. Mix thoroughly to ensure every piece is well-coated. Cover and leave to marinate in the fridge for at least 1 hour, or overnight for a deeper flavour.

Prepare the Rice: Rinse the basmati rice under cold running water until the water runs clear. Soak the rice in fresh cold water for 30 minutes, then drain completely. In a large pot, bring 2 litres of water to a boil with 1 tsp salt and the whole spices (bay leaves, cardamom, cinnamon, cloves). Add the drained rice and cook for 5-7 minutes, until the rice is about 70% cooked. It should still have a firm bite. Drain the rice immediately and set it aside.

Fry the Onions (Birista): While the rice is cooking, heat the oil or ghee in a large, heavy-bottomed pot or Dutch oven over a medium heat. Add the thinly sliced onions and fry for 15-20 minutes, stirring frequently, until they are deep golden brown and crispy. Be patient here, as this step builds a huge amount of flavour. Remove half of the fried onions with a slotted spoon and set aside for garnish.

Cook the Chicken: Add the marinated chicken to the pot with the remaining onions. Cook over a medium-high heat for 10-12 minutes, stirring occasionally, until the chicken is lightly browned and the marinade has thickened into a rich gravy.

Layer the Biryani: Turn the heat down to low. Spread the cooked chicken evenly across the bottom of the pot. Sprinkle over half of the chopped mint and coriander. Top this with the par-boiled rice, spreading it out in an even layer.

Add the Finishing Touches: Sprinkle the reserved fried onions, the remaining mint, and coriander over the rice. Mix the saffron threads with the warm milk and drizzle this mixture over the top of the rice in a few spots to create patches of colour. Finally, drizzle the melted butter or ghee over everything.

'Dum' Cook the Biryani: Cover the pot with a tight-fitting lid. What works best for me is to place a clean tea towel under the lid to create a better seal and absorb excess steam. Cook on the lowest possible heat for 20-25 minutes. This gentle steaming process, known as 'dum pukht' cooking, allows the flavours to meld together beautifully.

Rest and Serve: Turn off the heat and let the biryani rest, still covered, for 10 minutes. Before serving, gently fluff the rice with a fork, mixing the layers slightly so you get a bit of everything in each portion.