1 onion, thinly sliced
150ml vegetable oil
2½ tbsp sweet paprika
1 tbsp each black peppercorns, cumin seeds and coriander seeds
2½ tsp each ground turmeric and ground chilli
A generous pinch of grated nutmeg
3 cardamom pods
2 star anise
1 cinnamon quill, broken into rough pieces
2 long dried chillies, broken into rough pieces
1 fresh bay leaf
500g thick yogurt
½ cup each finely chopped mint and coriander, plus extra coriander to serve
1½ tbsp finely grated ginger
4 garlic cloves, finely chopped
4 chicken thighs, halved through the joint
400g basmati rice
50g butter, diced
A pinch of saffron threads
Fry onion in 120ml oil in a saucepan over medium-high heat, stirring occasionally, until golden, 6-8 mins.
Transfer to a bowl and cool.
Dry-roast spices, chilli and bay leaf over medium heat, then pound with a mortar and pestle to a fine powder.
Add to onion along with yogurt, herbs, ginger, garlic and 2 tsp salt. Mix well.
Add chicken, stir to coat, cover and refrigerate overnight to marinate.
Spread chicken mixture in the base of a heavy-based casserole with a tight-fitting lid.
Bring rice, 20g butter, remaining oil and enough well-salted water to cover by 2cm to the boil in a saucepan over medium-high heat.
Drain and spread over chicken.
Bring milk, saffron and remaining butter to the simmer in a saucepan over medium-high heat, then pour over rice, cover with foil, then the lid.
Cook over low heat until rice is fluffy and chicken is cooked through, about 1 hour.
Stand for 15 mins without removing the lid, then garnish with fried shallots and coriander sprigs. Serve with lemon wedges.