For the spaetzle, boil 3-4 l salted water. Peel and chop the onion. Clean the mushrooms, wash briefly and chop smaller. Fry in 1 tbsp. hot oil for 3-4 minutes. Fry the onion. Season with salt and pepper.
Add 400 ml water and cream, bring to the boil. Stir in stock and thicken with sauce thickener. Season to taste again.
Cook spaetzle in boiling salted water according to package instructions. Pat cutlets dry and fry in 2 tbsp. hot oil on each side for approx. 3 minutes. Season with salt and pepper. Wash and chop parsley.
Melt the butter. Toss the parsley in it. Swivel drained spaetzle in it. Arrange everything.