Place the whole cauliflower on a baking tray and drizzle over a splash of oil (or spray with cooking oil spray as I did), then season well and roast for around 1 hour, 30 minutes or until golden.
While you wait, in a large deep based pan, spray with oil spray and gently saute the onions and garlic until softened.
Add the cumin seeds and continue to gently fry for 2 minutes to release the flavours.
Add the cumin seeds and continue to gently fry for 2 minutes to release the flavours.
Now break up the remaining cauliflower in to bit size pieces and add to the soup and the chickpeas, spinach and lemon juice then stir and bring to a simmer.
Finally, stir in the greek yogurt and I served with some fresh parsley.