Cook the onion and sliced leek in the meat stock until the vegetables are almost cooked through. Then puree with a hand blender. In the meantime, sear the minced meat and season with salt and pepper. Put the minced meat in the vegetable stock and add the mushrooms. Let simmer for about 5 minutes.
Then turn off the stove and add the two processed cheeses. Stir with the whisk until the cheese has melted. Now serve! Delicious party soup that everyone likes.