Place the chicken thighs into a bowl with the Greek yoghurt, garlic, fresh ginger, tomato puree, turmeric, garam masala, ground coriander, ground cumin, cinnamon powder, cardamom pods, mild chilli powder, green chilli and sea salt. Mix well, cover and leave to marinate for at least 2 hours, or overnight.
Rinse the basmati rice thoroughly until the water runs clear. Place into a pan, cover with water and add the ground cumin, cardamom pod and bay leaf. Bring to the boil and cook for 5–6 minutes until just al dente. Drain well, then spread onto a tray to steam dry.
Preheat the oven to 180°C.
Warm the milk gently, add the saffron and leave to infuse while preparing the rest of the dish.
Heat the vegetable oil in a pan over a medium heat. Add the sliced onions and a little sea salt, then cook slowly until deep golden and crisp. Transfer to kitchen paper.
Heat the ghee in a heavy pan or ovenproof dish over a medium heat. Add the marinated chicken and cook for 5–6 minutes until lightly coloured on all sides.
Turn off the heat and spread the rice evenly over the chicken.
Drizzle over the saffron milk, then scatter over the fresh coriander, fresh mint and crispy onions.
Cover tightly with foil and a lid, if using, then bake for 20 minutes.
Leave to rest for 5 minutes before serving. Serve with a little Greek yoghurt.