In a large skillet over medium heat, add all the ingredients and mix really well. Bring to a boil. Taste and adjust salt and flavor. You can add more garam masala if you like or some ground cumin and ground coriander for additional flavor. (Old spices have much less flavor payoff so you might have to adjust as needed. I use fresh spices and spice blends and often use less than listed)
Continue to cook for another 5-8 minutes to thicken and switch off the heat.
If the sauce is not thickening enough you can add 2 teaspoons of flour mixed with 2 tablespoons of water or 1 teaspoon of cornstarch mixed with 1 tablespoon of water (for gluten-free) and mix it in while it’s still boiling. This will help the sauce thicken faster.
The sauce will thicken more as it cools so you don’t want it too thick while it’s hot.Serve the butter chickpeas garnished with cilantro, lemon juice, and sliced green chilies or with rice or quinoa or flatbread, or naan. You can also add a garnish of non dairy cream.