1. Melt the butter in a saucepan over a medium heat. Add the onion and cook, stirring frequently, until softened. Add the parsnips, carrot, and potato. Sprinkle in the flour and curry powder and stir for 2 minutes.

2. Gradually stir in the stock. Turn up the heat and bring to a boil. Reduce the heat to low. Cover and simmer gently for 40 minutes, or until the vegetables are tender.

3. Turn the heat off, uncover, and allow the soup to cool slightly. Purèe the soup into a blender or food processor. Season with salt and pepper. Pour back into the pot and reheat before serving.

4. To serve, ladle into bowls. Top each with a swirl of creme fraiche and a sprinkle of chopped parsley.