Process spinach, cavolo nero, and cilantro in a food processor until finely chopped. Instead of cavolo nero, you can also use more spinach or another green of choice, like mustard greens, bathua, or collard greens.
Heat oil in a pan over medium heat. Add the onions and cook for 5 minutes or so, until more golden and translucent.
Add the garlic and green chilis. Cook for another 2 minutes.
Add ground spices: cumin, coriander, cinnamon. Combine well for a minute.
Add the greens, lemon juice, and salt. Cook for 10 minutes, stirring occasionally. Add the butter beans and let them cook in the saag for a few minutes. Finish with kasoori methi and serve with a flatbread of choice or rice!