Heat a small frying pan, add the cumin seeds and toast for about 2 minutes, giving a little shake of the pan a couple of times. Set aside.
Heat the oil in a large saucepan, add the onion and cook for about 8 minutes, until they are golden. Then add the ginger, garlic and red chilli, chopped cilantro/coriander stalks. Cook for about two minutes then add the turmeric, garam masala, ground coriander and cumin seeds, mix well and cook for about 1 minute. Making sure not to burn the spices.
Now pour in the tin of tomatoes and stir, add the butternut squash, peppers and chickpeas, and stock. Add the salt and pepper. Leave to simmer for about 30 minutes stirring occasionally so it doesn't stick to the bottom of the pan. Check the seasoning again.
After 30 minutes the curry should be reduced by a third and the butternut squash should be cooked.
Turn off the heat and then start adding the spinach. Add it one large handful at a time, gently stir it in and as soon as it wilts down. Repeat with the remaining spinach. Once all the spinach has been added the curry is ready to serve.
Serve with rice and/or naan and some extra coriander leaves.