1. Melt the butter in a heavy based pot on medium heat, Induction setting 6. Add the leeks and shallots and sauté until translucent, approximately 5 minutes. Add flour and stir, cooking briefly.
2. Add the vegetable stock to the pot, mixing with the flour until combined. Increase the temperature to medium-high heat, Induction setting 7 and bring to the boil. Reduce the temperature to medium heat, Induction setting 6 and simmer for 5 minutes.
3. Add cooked potatoes, herbs, spinach and watercress. Simmer for a further 2-3 minutes to wilt the greens and warm through the potatoes. Season with salt and pepper to taste.
4. Puree with a stick blender and then stir in the cream.
5. Garnish with extra herbs before serving.

• It is a popular tradition in Germany to eat this green soup on Gruendonnerstag (or Maundy Thursday).
• Traditionally, the soup is made with a combination of leek, dill, parsley, spinach, watercress, dandelion, chervil and sorrel; however various leafy greens can be used, including kale and silverbeet.