1. Combine mustard, 1 tablespoon parsley, 1 1/2 teaspoons thyme, and chicken in a large zip-top plastic bag; toss well to coat. Chill 8 hours or overnight.
2. Remove chicken from bag, and discard marinade. Sprinkle chicken with salt and black pepper. Heat olive oil in a large Dutch oven over medium-high heat. Add chicken to pan, and cook 5 minutes on each side or until browned. Remove from pan.
3. Add chopped onion to pan, and sauté 5 minutes or until tender, stirring frequently. Add garlic to pan, and sauté 1 minute, stirring constantly. Stir in wine and chicken broth, scraping pan to loosen browned bits. Stir in 1 tablespoon parsley and remaining 1 1/2 teaspoons thyme. Return chicken to pan. Cover, reduce heat, and simmer 25 minutes or until chicken is done. Remove chicken from pan with a slotted spoon. Keep warm.
4. Cook sauce, uncovered, over medium heat 4 minutes or until slightly thick. Pour sauce over chicken, and sprinkle with remaining 2 tablespoons parsley.