A rich, korma-style chicken curry thickened with ground cashews and deeply caramelized onions, spiced with garam masala and cardamom and finished with cream or yogurt.
In a large pot, melt the ghee or butter over medium heat. Add the onion and cook until golden and caramelized, about 25 minutes (lower the heat if it's browning too quickly).
Meanwhile, in a food processor, finely grind the cashews (with a little water if needed) to a fine consistency. Set aside.
When the onions are soft and golden brown, add the garlic and jalapeño and sauté 1 minute. Add the garam masala, cinnamon, pepper and salt and sauté 1 minute more. Stir in the cardamom pods and diced tomatoes and cook until the oil begins to shimmer on the surface, 3–5 minutes.
Add the chicken thighs, ground cashews and water; bring to a boil over medium-high heat, then reduce to low, cover the pot and simmer until the chicken is cooked through, about 25 minutes.
Uncover the pot and increase the heat until the curry thickens to your desired consistency (about another 15 minutes). Stir in the cream or yogurt, then taste and add more salt until the seasoning is right — the spices and tomato should taste vibrant, not flat. Top with chopped cilantro.
Notes
Caramelize the onions: A full 25 minutes builds the deep, sweet base — don't rush it.Cashews thicken and enrich: Ground cashews give a creamy, korma-like body; almond butter is a quick substitute.Crack the cardamom: Cracking the pods releases their aroma; fish them out before serving if you like.Season at the end: Add salt until the spices taste vibrant rather than flat.