Boerenkool Stamppot is the perfect hearty meal to warm up during the cold Dutch months. Although there are many variants of Stamppot (e.g., with carrots and onions – Hutspot), the one with kale is the most famous.
Stamppot is traditionally prepared by boiling the vegetable together with the potatoes, then draining and mashing everything together, adding butter and milk for creaminess.
Place the potatoes and kale in a large pot. Cover with water until the potatoes are just submerged. Add a pinch of salt.
Bring to a boil and cook for about 20 minutes until the potatoes are tender (the kale will cook along with the potatoes).
If using Rookworst, place the smoked sausage on top of the potatoes about 15 minutes before the end of cooking to heat it in the broth.
Drain the potatoes and kale, but reserve about 100 ml of the hot cooking water.
Add the butter, warm milk, and reserved water (as needed, to achieve desired consistency) to the pot with the potatoes and kale.
Use a potato masher ('stamper') to mash everything. Stamppot should be coarse and rustic, not a creamy purée.
Season the Stamppot with salt, black pepper, and nutmeg. Mix well.
On the plate, make a small well in the center of the Stamppot and fill it with a spoon of hot butter, sausage drippings, or a rich gravy (known as jus).
Slice the Rookworst and place it on top of the Stamppot. Serve hot.