Fry the frozen mushrooms in a dry pan on high heat until the liquid has evaporated. Fresh, cleaned and finely chopped porcini mushrooms in Butaris until the mushrooms are almost soft.
Now add the onion and cook until translucent. Pour in the milk and thicken with the cornstarch. Season to taste with pepper, salt and seasoning, add parsley. Stir in the creme fraiche.