1. Whisk 5 teaspoons flour and broth in a small bowl until smooth.
2. Place the remaining flour in a shallow dish. Season chicken with 1/4Â teaspoon salt and pepper and dredge both sides in the flour. Heat 2 teaspoons oil in a large nonstick skillet over medium heat. Add the chicken and cook until browned and no longer pink in the middle (2-3 minutes per side). Transfer to a plate; cover and keep warm.
3. Heat the remaining oil in the pan over medium-high heat. Add mushrooms and cook, stirring, until they release their juices and begin to brown, about 5 minutes. Transfer to a plate. Add garlic and wine to the pan and cook until reduced by half, 1 to 2 minutes. Stir in the reserved broth-flour mixture, lemon juice and the remaining 1/4 teaspoon salt. Bring to a simmer and cook, stirring, until the sauce is thickened (5 minutes).
4. Stir in parsley, capers, butter and the reserved mushrooms. Measure out 1/2 cup of the mushroom sauce. Toss the pasta in the pan with the remaining sauce. Serve the pasta topped with the chicken and the reserved sauce.