Preheat the oven to 160°C / gas mark 3.
To make the spinach sauce, melt the butter in a large nonstick pan. Add the cornmeal, garlic, chopped chillies and ginger. Cook for a minute until aromatic. Pour in the blended spinach mixture and add the ground cumin. Cook on a medium-low heat for five minutes. Keep a lid handy as it may splutter. Stir in the cream and set aside.
For the white sauce, melt the butter in a pan, add the flour and cook until the flour just begins to colour slightly. Turn the heat off and gradually add the milk, whisking all the time. Put the pan back on the heat and add the salt and pepper. Continue to cook and whisk until thick, smooth and glossy. Add 150g of cheese and whisk again.
Begin layering the lasagne in a deep ovenproof dish, starting with a spread of spinach sauce on the bottom of the dish. Cover with lasagne sheets, white sauce, another layer of lasagne, then more spinach mixture. Continue to layer in this way until all of the ingredients are used up, finishing with white sauce. Finally, sprinkle the top with the remaining cheese.
Bake for around 40 minutes until golden on top. Allow to rest for five to ten minutes before serving.