Peel and chop the onion. Fry in hot fat. Dust with flour and sweat. Stir in 1/4 l water and milk. Bring to the boil and add the stock. Simmer over low heat for about 5 minutes while stirring
Meanwhile cook the ribbon noodles in plenty of boiling salted water for 10-12 minutes
Clean and wash mushrooms. Wash parsley and chop finely, except for something to garnish. Melt the cheese in flakes in the sauce. Season to taste with pepper and a little salt
Drain the pasta and serve with the cheese sauce. Finely slice the mushrooms. Sprinkle with parsley and garnish