Place a large, covered pot of water over high heat and bring up to a boil for the egg noodles. Season water with salt and cook the noodles according to the package directions.
While the water is coming up to a boil, preheat a large skillet over high heat with 2 turns of the pan of EVOO, about 2 tablespoons. Add the chicken, spreading it out in an even layer, and season with salt and pepper. Cook 3 minutes on each side.
In another large preheated skillet, heat remaining 2 tablespoons of EVOO and add the mushrooms. Cook until tender, stirring occasionally. Once the mushrooms have browned up, season them with salt and freshly ground pepper.
Melt 1 tablespoon of butter or add 1 tablespoon of EVOO in the mushroom skillet, then add the flour. Cook for 1 minute and whisk in 1 1/2 cups chicken stock, the heavy cream and Dijon mustard.
While the mushroom skillet is coming up to a bubble, add remaining 1/2 cup chicken stock to the skillet with the chicken and scrape the bottom of the pan with a wooden spoon to loosen up the browned bits on the bottom of the skillet. Transfer chicken and the liquid to the skillet with the mushrooms. Stir to combine, and cook about 1 minute more, or until thick.
Drain and then return the noodles to the pot and add the 2 tablespoons of butter a little salt, pepper, chives, and parsley and stir to melt the butter.
To serve, divide the noodles between four serving plates, spoon the chicken and mushrooms over the noodles and garnish with chives. Serve with a green salad alongside.