Delicious Indian-spiced chicken dish, that's lightly creamy from the yogurt. If you like a bit more heat, increase the amount of cayenne pepper, to taste. You can substitute bone-in/skin-on chicken breasts or thighs or boneless/skinless chicken, but the cooking time will vary, so check regularly during cooking. The juices should run clear when a knife is inserted in it.
Preheat oven to 325° F. with rack in lower 1/3 of oven.
Pan chicken dry and season with salt and pepper. Heat 1 Tbsp. oil in an oven-safe pan (with a lid, such as a Dutch oven) on stove-top over medium-high heat. Brown chicken on both sides until golden and remove to a plate.
Add butter and onions to pan (don't remove drippings unless excessive). Cook, stirring regularly, until onions are soft and golden brown, about 10 minutes. (Don't rush browning the onions, as cooking them to golden adds great flavour to the dish). Stir in garlic, ginger and spices. Cook, stirring constantly, about 1 minute. Stir in chickpeas and 2 cups of broth. Return chicken to pan and any accumulated juices. Liquid should cover chicken by about 2/3. If not, add a bit more broth to top up. Bring liquid to a simmer, then cover and transfer to the pre-heated oven. Cook until chicken is fork-tender, about 45 minutes, depending on the cut of chicken you used.
Remove from oven and transfer chicken to a plate. Cover with foil to keep warm. To hot liquid in pot, add spinach. Cover and let stand about 5 minutes, or until spinach is wilted. Stir in yogurt. Taste and season with salt and pepper, to taste. (If sauce is not as thick as you'd like, mix a bit of the sauce with a couple of teaspoons of cornstarch to make a paste. Add a bit at a time to the warm sauce and stir until desired thickness). Return chicken to pot and warm over low heat (do not boil or yogurt may curdle).
Transfer chicken to a serving platter and pour spinach and chickpea sauce over. Sprinkle with chopped cilantro or parsley.