In large non stick frypan on high melt butter. Place flour in pie pan. Add chicken and turn to coat. Place chicken in frypan and cook, turning about 5 minutes to brown well on both sides. Stir in onion, mushrooms and any unused flour. Reduce heat to med and cook, stirring until onion is golden, about 5 minutes.

In small bowl whisk together chicken broth and mustard. Pour mixture into frypan and stir. Bring to boil, reduce heat to simmer and cook about 5 minutes. Stir in sour cream and parsley. Simmer 2 more minutes. Season with salt and pepper. Server over noodles.