Bring a large pot of water to a boil, salt generously then add the noodles and cook while you are preparing the dish. Once the noodles are cooked per package directions, drain and hold.

In a large skillet or sauté pan, melt three tablespoons of the butter over high heat. Once melted, add mushrooms, one teaspoon of the salt and one-half teaspoon of the pepper and cook for about ten minutes. The mushrooms will give up some liquid then absorb it back in but keep stirring and cook for the full ten minutes or until they are nicely browned. Add one quarter cup of the wine, scrape the bottom, and once evaporated, pour the mushrooms into a large bowl and hold.

Add two more tablespoons of butter to the pan and reduce heat to medium. Once the butter melts, add the onions and cook for about five minutes or until soft and starting to brown. Add to the bowl with the mushrooms.

Toss the chicken pieces with the flour and remaining salt and pepper until fully coated.

Add two more tablespoons of butter to the pan and add half the chicken pieces, not touching each other. Cook for 2-3 minutes per side or until cooked through and add to the bowl with the mushrooms and onions.

Add the remaining tablespoon of butter and once melted, add the remaining chicken and cook as before then remove to the bowl.

Add the remaining wine to the pan and scrape the bottom. Once evaporated, add the stock and all of the contents from the bowl.

Once everything is hot and bubbly, add in the mustard and sour cream and stir to combine. Cook for a few minutes to thicken then remove from heat and serve over the cooked noodles with chopped parsley as garnish.