Sprinkle the chicken with the thyme. Heat the oil in a large nonstick skillet over medium-high heat. cook the chicken for 5 to 7 minutes, turning once, or until well browned. Remove to a plate.

Cook the onions and scallions in the same skillet, stirring, for 5 to7 minutes or until browned. Add the vinegar and cook for 1 minute, stirring to loosen any brown bits. add the broth and bring to a boil.
Returm the chicken to the skillet, reduce the heat to medium low, cover, and simmer for 10 minutes, or until a thermometer inserted in the thickest portion registers 160°F fahrenheit in the juices run clear

Place the spinach on a serving platter. Top with the chicken and onion mixture and sprinkle with the cheese.