Place a cooking pot on high heat. Add the water and allow it to boil.
When water starts boiling, add salt, stock cubes, cayenne pepper and the roughly chopped leek, onion, celery, potato and broccoli stalks. Leave the florets aside for now.
Cover and boil for 15-20 minutes on medium heat until veggies are nice and soft.
Remove the lid, add the broccoli florets and cook for another 5 minutes.
Add the cheese in and either transfer the soup to a blender or blend it with an electric hand blender.
Season with some cayenne pepper and salt if needed and serve.