Peel the parsnips and cut into cubes. Peel and dice the onion as well. Wash the kale and cut into bite-sized pieces.
Melt 2 tablespoons of butter in a large pan and fry the parsnip cubes over medium to high heat for about 6 minutes until they are lightly brown, stirring occasionally. Add the onion and let it become translucent for about 2 minutes, stirring occasionally. Add the stock and thyme to the pan and bring to the boil. Season with salt and pepper and cook the parsnips covered over a low heat for about 8 minutes until they are soft. Put the parsnips in a bowl and wipe the pan clean.
In the meantime, cook the kale in a saucepan with salted water for about 2 minutes until soft. Drain and let cool under running water. With the help of a towel, squeeze the water out of the kale to get it completely dry. Then add the kale to the parsnips.
In the pan in which the parsnips were cooked, melt the remaining 2 tablespoons of butter and let them brown lightly over a medium heat for about 4 minutes. Stir in the flour and cook for 1 minute. Now stir in milk, mustard flour and grated nutmeg. Season with salt and pepper. Let the sauce simmer for about 6 minutes over medium heat, stirring constantly, until it thickens and becomes creamy. Season the sauce with the spices. Remove the pan from the heat and add the parsnip and kale mixture. Stir well until all of the sauce is covered and serve.
The Boss Kitchen editorial staff oversees content review, fact-checking, and recipe verification across the site. Published articles pass through the editorial team before going live, ensuring ingredient lists, techniques, cooking times, and nutritional claims hold up in a home kitchen. The team coordinates contributions across the site writers, handles reader corrections, and maintains consistency in measurement conventions, safety guidance, and dietary labeling. Posts under this byline typically represent team-reviewed reference material, site announcements, or editorial roundups rather than individual-author features, and they are held to the same sourcing standards as bylined recipe and product coverage.