Measure the yogurt into a large mixing bowl. Add the spices and sea salt, then whisk until combined. Pour the drained and rinsed chickpeas into the bowl, folding the chickpeas into the yogurt marinade until they are completely coated. Set the chickpeas aside while you start the sauce.
Make the cashew cream. Combine the raw cashews and 1 cup of water in a high-speed blender. Blend until completely smooth.
Peel and thinly slice the onion, and mince the ginger and garlic.
Heat a large pot or Dutch oven over medium heat. Add the coconut oil, pushing it around with a wooden spoon to coat the bottom of the pot. When the oil is shimmering, add the sliced onions. Cook the onions until soft and translucent, about 10 minutes. Add the ginger and garlic, then cook for a further two minutes.
Add the marinated chickpeas to the pot, making sure to scrape as much of the marinade out of the bowl as you can. Stir well and cook for a further two minutes.
Pour in the passata and cashew cream, stirring to combine, then stir the coconut sugar into the sauce. Bring the butter chickpeas to a boil, then reduce to a simmer, cover, and cook for 20 minutes. Stirring often to avoid burning. If your sauce feels too thick, you can add a bit of water to loosen it.
Stir the butter into the butter chickpeas until it has melted and is fully incorporated into the sauce. Taste and adjust the seasoning to your desire.
Serve the butter chickpeas with rice, warm naan bread, and fresh cilantro.