1Cook pasta according to package directions, omitting salt and fat; drain.
2Heat a Dutch oven over medium-high heat; coat with cooking spray. Sprinkle chicken with 1/4 teaspoon salt and 1/4 teaspoon pepper. Add the chicken to the Dutch oven; saute 4 minutes, turning to brown on all sides.
3Combine 1/4 cup stock and flour. Add the flour mixture, 1/4 cup stock, and half and half to the pan. Bring to a boil. Cook 2 minutes. Remove from heat; stir in 1/4 teaspoon salt, 1/4 teaspoon pepper, mascarpone, and 2 tablespoons parsley.
4Heat a skillet over medium heat; coat with cooking spray. Add onion and garlic; cook 5 minutes. Add thyme and mushrooms, cook 8 minutes. Stir in 1/4 teaspoon salt, 1/4 teaspoon pepper, vinegar, and mustard; cook 30 seconds. Add pasta and chicken mixture; toss. Sprinkle with 2 tablespoons parsley.