Clean the mushrooms, wash if necessary and cut into slices. Peel and finely dice onion
Heat the oil in a pot. Sauté the onion in it. Add mushrooms and fry for about 5 minutes. Season with salt and pepper. Sprinkle with flour and sauté briefly. Deglaze with 3/4 l water and milk while stirring, bring to the boil. Stir in broth. Dice cheese roughly, add to the soup and melt while stirring. Season soup to taste
Wash the parsley and pluck the leaves from the stems. Add to the soup except for something to garnish. Cut bread into triangles. Heat the fat in a pan. Roast the bread in it until golden brown. Garnish the soup with the remaining parsley. Add the toasted bread
The mushroom-cheese soup can be precooked well. Then cool the soup quickly (e.g. in a cold water bath). Store in the refrigerator