Trim excess fat from the chicken thighs and cut into bite-size pieces (about 1.5-inch). In a bowl combine yogurt, ginger paste, garlic paste, 2 teaspoons salt and black pepper. Add chicken, mix to coat thoroughly, cover and refrigerate for at least 30 minutes, ideally 1–2 hours.

Base and aromatics

Heat a large heavy skillet or Dutch oven over medium heat. Add vegetable oil and butter. When butter melts and starts to sizzle, add crushed cardamom, cinnamon stick and bay leaf and fry for 30 seconds until fragrant.

Add the finely chopped onion and 1 teaspoon salt. Cook, stirring occasionally, until onion is soft and golden brown, about 12–15 minutes; lower the heat if browning too quickly to avoid burning. This slow browning builds the sauce flavor.

Khorma spice paste

While the onions cook, soak the blanched almonds and shredded coconut in 4 tablespoons warm water for 10 minutes to soften. In a small blender or food processor, combine soaked almonds and coconut (with any remaining soaking liquid), green chili, cilantro, mint (if using), ground coriander and ground cumin. Blend to a smooth, thick paste — add 1–2 tablespoons additional water if needed to achieve a smooth consistency.

Taste the paste for balance: it should be aromatic, nutty and slightly tangy. Set aside.

Cooking the chicken

Increase heat to medium-high. Add the marinated chicken pieces to the pan with the browned onions in a single layer. Sear undisturbed for 2–3 minutes, then stir and cook until chicken is mostly cooked through, about 4–5 minutes total. Do not fully cook — it will finish in the sauce.

Lower heat to medium. Stir in the prepared khorma spice paste, turmeric, chili powder and tomato paste. Cook and stir for 2–3 minutes to remove raw paste flavor and allow spices to bloom.

Pour in the chicken stock (or water), scraping up any browned bits from the pan. Bring to a gentle simmer, cover partially and simmer for 8–10 minutes until chicken is tender and the flavors have melded.

Finishing

Stir in the heavy cream (or coconut milk) and sugar (if using) and simmer gently uncovered 3–4 minutes until sauce is rich and slightly thickened. Taste and adjust seasoning with remaining 1 teaspoon salt and lemon juice.

Sprinkle garam masala over the curry, give a final stir, remove cinnamon stick, bay leaf and whole cardamom pods if desired. Garnish with chopped cilantro and slivered almonds or pistachios.

Serve hot with steamed basmati rice, naan or parathas.