I like spinach. Luckily it is also a great source of iron which can be lacking in vegetarian diets. For the maximum Iron boost from this soup serve it with a glass of OJ the Vitamin C aids Iron uptake. From BBC good food magazine.
Melt the butter in a large lidded saucepan, add the onion and garlic and fry gently for 5-6 minutes until softening.
Stir in the potato and continue to cook gently for 1 minute.
Pour in the stock and simmer for 8-10 minutes until the potato starts to cook.
Pour in the milk and bring up to a simmer, then stir in half the spinach and the lemon zest.
Cover and simmer for 15 minutes until the spinach has completely wilted down. Allow to cool for about 5 minutes.
Pour the soup into a blender (preferably) or food processor, add the remaining spinach (this will keep the soup bright green and fresh tasting) and process until silky smooth (The soup may now be frozen for up to 1 month. Defrost in the microwave or overnight in the fridge.)
Return to the pan and reheat. Taste and season with salt, pepper and nutmeg. You may like to dilute the soup with a little extra stock if too thick. Ladle the soup into bowls and swirl in the cream.