For the Schupfnudelpfanne with mushrooms, first prepare the Schupfnudeln as in the basic recipe.
Peel and dice the onion. Clean the mushrooms (carefully, with a brush).
Heat sunflower oil in a frying pan. Fry onion until translucent, then add mushrooms and fry for about 5-10 minutes. Fold in sour cream or crème fraiche. Season with salt and pepper.
Fry the Schupfnudeln in another pan in a little oil. Portion the Schupfnudeln on plates or in bowls and spread the sauce on top. Garnish the Schupfnudelpfanne with mushrooms with Parmesan shavings and serve.