Combine first 5 ingredients in a shallow dish; set aside.
Place chicken between 2 sheets of heavy-duty plastic wrap; flatten to 1/4-inch thickness, using a meat mallet or rolling pin. Lightly coat both sides of chicken with cooking spray; dredge chicken in breadcrumb mixture.
Melt margarine in a large nonstick skillet coated with cooking spray over medium-high heat. Add chicken; cook 4 minutes on each side or until done. Remove chicken from skillet. Set aside; keep warm. Add lemon slices to skillet; sauté 30 seconds. Add broth, parsley, and lemon juice; cook 1 minute. Spoon sauce over chicken.