Place greens in a blender or food processor a little at a time, drizzling it with the boiling water as you go so it wilts and you can fit it all in. Process until very finely chopped, but not pureed. Set aside.
Heat ghee or butter in a large pot over medium heat. Add chopped onion and half the salt; cook, stirring often, until very soft and golden. Reduce the heat if onions are browning - low and slow is the goal.
Add the ginger and garlic and cook until fragrant, about 1 minute.
Add the turmeric, cumin and fenugreek powder and cook 1 minute more.
Stir in the spinach (and/or other greens), bring to a simmer, then add cream or yogurt, lemon juice and remaining salt.
Gently stir in paneer and heat through.
Video
Notes
Substitutions for cream: Instead of whipping cream, you can use thick greek yogurt or coconut milk. Just don't swap in regular milk or half-and-half cream, as the acid will make it curdle.A trick to make storebought paneer tastier: commercial paneer can vary widely in how much salt and flavor it has. Take a taste. If it tastes bland, try this flavor booster: cube the paneer and saute it first in a tablespoon or two of melted butter or ghee. Sprinkle with a little salt as it cooks. Transfer it to a plate while you finish the recipe in the same pan.