Peel the potatoes, cut into 2 cm cubes and the leek into rings. Dice the onions.
Melt 30 g butter in a saucepan. Sweat the onions in the butter until translucent, add the potato cubes and the white leek rings, sweat briefly and fill up with 1 1/2 liters of chicken stock. Simmer over medium heat for 20 minutes.
Form small balls from minced meat, 1 tablespoon parsley, salt and pepper and fry on all sides in 30 g butter. If you like the balls tastier, add the egg, some bread flour and half a teaspoon of mustard to the mince before frying them.
Finally stir the processed cheese into the soup, let it melt and possibly (depending on your taste) season a little, maybe add a little sour cream and cook for 5 minutes. Add the meatballs, let them steep and serve.