This dish is known in India as Saag Paneer. Its one of my favourite ways with spinach.
Blanch the spinach leaves in hot water for about 3 minutes until wilted. Drain in a colander and run under cold water until cool. Drain well, then chop finely or blend to a smooth paste as preferred.
Heat the oil in a large non-stick frying pan. Add the cumin seeds and fry for about 30 seconds, then add the onion and fry for a further 6 minutes over a gentle heat until soft. Add the ginger, garlic and whole chilli and cook for a minute, then add the coriander and a pinch of salt.
Cook for 30 seconds then add the spinach to the pan and a little water if needed. Bring to the boil and simmer for 3 minutes.
Add the paneer, garam masala and cream. Stir together and cook for a few minutes until the spinach is creamy. Stir in lemon juice to taste before serving.