In a pan or a pot, heat oil. Add onion with ginger, garlic and some salt and saute on low/medium heat until dark brown. (If you prefer the dark gravy cook as brown as possible. Switch off just before they start to burn.)
Add the crushed/pureed tomatoes with little salt.(I have just blended fresh tomatoes here.)
Continue cooking with little salt, once tomatoes have soften.
Add the spices(curry powder,garam masala and red chilli/paprika powder).
Continue cooking until the masala has mixed well.
Add chickpeas to curry mix and hot water, Cover and cook for 10-15 minutes.
Add coconut milk to the chickpea curry. You can adjust it according to your taste.
Add the chopped spinach leaves and turn off the heat.