1. Set a saucepan on a medium heat and sauté the onion for a couple of minutes before adding the leek and broccoli. Add a splash of boiling water, season and cover for around 6 minutes or until the broccoli is tender.
2. Meanwhile, blanch the spinach in a pan of boiling water for 30 seconds. Remove, drain and squeeze out all the water before chopping. If you want the green to stay super fresh, put the spinach in an ice bath before chopping to halt the cooking process.
3. Add all the vegetables, together with the chicken stock to a blender (I swear by my Magimix Le Blender).
4. Pass through a fine sieve for a silky finish (you needn’t feel obliged to though).
5. Put back in a pan, add a the chilli flakes, check the seasoning and reheat before serving with a slice of fontina cheese which will melt gloriously into the soup.