Remove Skin From Turkey. Pat Turkey Dry With Paper Towels; Spray Turkey With Nonstick Cooking Spray. Place Breast Side Up In A Slow Cooker. Squeeze Half Of The Lemon Over Turkey; Sprinkle With Lemon-Pepper And Garlic Salt. Place Lemon Halves Under Turkey. Cover And Cook On Low For 5-7 Hours Or Until Meat Is No Longer Pink And A Meat Thermometer Reads 170 Degrees F. Remove Turkey And Keep Warm. Discard Lemon. For Gravy, Pour Cooking Liquid Into A Measuring Cup; Skim Fat. In A Saucepan, Combine Cornstarch And Broth Until Smooth. Gradually Stir In Cooking Liquid. Bring To A Boil; Cook And Stir For 2 Minutes Or Until Thickened. Serve With Turkey.