Cut the kohlrabi into cubes and the carrots into slices. Put in a saucepan with the beef broth and bring to the boil. Season with salt, pepper and nutmeg to taste. Let cook until everything is firm to the bite.
In the meantime, finely dice the onion and place in a bowl with the egg to chop. Season with salt, pepper and cumin. Mix well and form small balls.
Stir the cream and cream cheese into the vegetables. As soon as the cream cheese is completely melted, put the meatballs in the pan. Simmer with the lid closed for approx. 10 minutes.
Cut the spring onions into fine rings and add just before serving.