Preparation of sauces: a sauce with mushrooms and Marsala

This sauce is not anything but a variant of salsa duello, which differs by the absence of tomato and addition of Marsala; excellent to accompany grilled meat or vegetables cooked by steaming. Ingredients: half a liter of broth with meat, 100g of mushrooms, an onion, 40g butter, a tablespoon of chopped parsley, a little white flour, meat extract, a pinch of nutmeg, 3 tablespoons dry Marsala, salt and pepper .
Preparation: In a small saucepan, dissolve 20g fate of butter, chopped Fry the onion and add the mushrooms very finely chopped and nutmeg; let cook for about ten minutes, in another pan melt the remaining butter; together the flour, Marsala and broth heated in which you added a teaspoon of extract of meat, then this filter consists of a pass, dropping it directly on the chopped mushrooms and onions, stir the whole, incorporating the chopped parsley, adjust salt and pepper.