Peel and finely chop the onion. Clean the mushrooms, possibly wash and halve them. Leave bacon in a large pan until crispy. Add onion and mushrooms and fry well. Add fat and let it melt in the pan.
Dust with flour and sweat it. While stirring, deglaze with stock and cream. Simmer for 5 minutes. In the meantime prepare noodles in boiling salted water according to package instructions. Wash parsley and shake dry.
Pluck leaves from the stems, except for a few for garnishing, and chop finely. Slice parmesan. Drain the pasta and let it drain. Add pasta and parsley to the sauce and sprinkle with parmesan.
Garnish with remaining parsley.