Sprinkle both sides of chicken with thyme and seasoned salt. Spray large nonstick skillet with no stick cooking spray. Heat over medium heat until hot. Add chicken; cook 5 to 6 minutes per side or until cooked through. Remove on serving platter; keep warm.
Spray skillet with cooking spray. Add onions; spray with cooking spray. Cook and stir 6 minutes or until browned.
Mix remaining ingredients in small bowl with wire whisk until blended. Add to onions. Bring to boil on medium heat; cook 2 minutes, stirring frequently. Spoon gravy over chicken.