1. Preheat oven to 400ºF. Lightly mist a 9-by-13-inch baking dish with cooking spray.
2. Sprinkle chicken lightly with salt and place 2 sage leaves on each chicken breast half. Wrap a slice of bacon around each piece of chicken and place chicken pieces in baking dish. Bake until chicken is cooked through and interior registers 165ºF on an instant-read thermometer, about 40 minutes.
3. Transfer chicken to a platter and cover loosely with foil to keep warm. Skim fat from juices in baking dish and pour them into a small saucepan. Place over medium-high heat and whisk in flour until a paste forms, 1 minute. Whisk in broth and lemon juice and bring to a boil. Reduce heat to medium and cook, whisking constantly, until sauce is smooth and thickened, about 2 minutes. Remove from heat. Whisk any juices that have accumulated on platter into sauce. Pour sauce over chicken and serve.