Bring a large pot of water to a boil. Season with salt.
Cut the chicken breasts into about 1-inch cubes. Season with salt, pepper, and garlic powder. Dredge in the flour and set aside on a dish.
In a large cast iron skillet warm one tablespoon of olive oil and one tablespoon of butter. Sear the chicken until golden brown on each side. Remove and set on a dish.
In the same pan add additional olive oil and butter. Add the mushrooms and cook for two to three minutes. Season with salt and pepper. Add in the garlic and cook for two minutes.
Deglaze the pan with marsala wine and allow it to cook out for two minutes. Add in the cream and chicken stock. Then add the chicken back into the pan and cook until the chicken is cooked through.
Sprinkle with the parsley and chives and taste for salt and pepper.
Drop the fettuccine into the boiling water. Cook for one minute shy of the time indicated on the package. Reserve 1 cup of pasta water. Strain the pasta and place it into the sauce with the chicken. Toss together.
Plate the pasta with extra sauce and top with Parmigiano Reggiano. Enjoy!