1. Place each breast half between 2 sheets of plastic wrap; pound to 1/4-inch thickness. Sprinkle with salt and pepper. Heat a large skillet over medium-high heat; coat with cooking spray. Place flour in a shallow dish; dredge chicken in flour. Add chicken to pan; sauté for 4 minutes on each side or until done. Remove chicken from pan.
2. Add butter and sage sprigs to pan; cook over medium heat until butter browns. Discard sage. Add shallots and thyme; cook for 30 seconds. Add lemon juice; cook for 30 seconds. Serve with chicken. Garnish with sage leaves, if desired.