Cut the beans diagonally into pieces approx. 2 cm long and cook in boiling salted water for 8-10 minutes, not completely soft. You should still have bite.
Heat the butter and bake it lightly with the flour, do not let it brown! Deglaze with the milk while stirring. Let it cook well, always stirring and refining with the cream. Season the sauce with salt, pepper and nutmeg, add the green beans and let it get hot.
In Denmark the classic addition to meatballs (see my recipe). Boiled potatoes are served with it.