Preheat your oven to 325°F (165°C) for the perfect cooking temperature.
In a large saucepan, simmer potatoes in water until tender, about 20 minutes.
Once the potatoes are tender, drain them and mash with butter, cream, nutmeg, salt, and pepper. Transfer the drained sauerkraut to a casserole dish and layer sliced kielbasa on top. Cover with the mashed potatoes mixture and dot with the remaining butter.
Simply bake in a preheated oven until warmed, 20 to 30 minutes.