Blanch the spinach in hot water for three minutes or until wilted. Drain into a colander and run cold water over it until cool. In a food processor or blender, blend to a smooth paste and set aside.
Heat the oil in a large non-stick pan. Add the cumin and fry for about 30 seconds, until fragrant, then add the onion and fry over a low heat for about six minutes, until soft. Add the ginger, garlic and chillies and cook for a further minute.
Add the ground coriander and salt to taste. Cook for another 30 seconds then add the spinach and a splash of water if necessary. The mixture should be loose but not watery. Bring to a boil and then simmer for three minutes.
Add the paneer cubes, garam masala and milk or cream. Stir and cook for a few minutes or until the spinach is nice and creamy. Stir in the lemon juice to taste. Serve with pilaff rice or naan bread.