To marinate the chicken

1. Combine all spice mix ingredients in a small bowl.
2. Cut chicken thighs into approximately medium-sized chunks. Aim to cut similarly sized pieces, so they all cook evenly.
3. Place yogurt, lemon juice and half of the spice mix into a medium bowl, then add the chicken and toss to coat. Cover and chill for at least 15 minutes, or up to 2 hours.
4. Reserve the remaining half of the spice mix for the sauce. Cover and chill until needed.

To make the curry sauce

1. Preheat the oven to 200°C, fan bake. Dice the onion finely.
2. Gently crush the coriander seeds, cardamom pods, bay leaves and chilli flakes with a rolling pin or a mortar and pestle.
3. Heat oil, butter or ghee in a large heavy-base pot or dutch oven over a high heat. Once hot, add the crushed whole spices — they should crackle and pop.
4. After about 30 seconds, lower the heat to medium and add the diced onion and tomato paste. Stir frequently and cook until the tomato paste is dark and onions are soft, about 4 minutes.
5. Add the reserved half of the spice and continue to cook, stirring frequently, until combined, thick and fragrant, about 4 minutes.
6. Pour in the crushed tomatoes and gently scrape the bottom of the pot with a wooden spoon to loosen any spices or tomato paste. Bring to a boil, then lower the heat and simmer for 10 minutes.
7. Add the cream and allow to simmer until the sauce is thick, stirring occasionally, about 20-30 minutes.
8. Meanwhile, place marinated chicken pieces on a rimmed baking tray, gently shaking off any excess marinade. Place on the top rack of the oven and cook for about 20 minutes, turning halfway through. The chicken should be cooked through and lightly charred.
9. Once sauce is thickened, add chicken tikka pieces and simmer for another 2 minutes to let the flavours combine fully.
10. Serve with basmati rice or garlic naan.