Directions

1. Heat 1 tablespoon oil in a large skillet over medium-high heat. Season chicken all over with garlic powder and 1/4 teaspoon each salt and pepper. Add the chicken to the pan and cook, turning once, until well browned on both sides, 6 to 8 minutes total. Transfer to a plate and keep warm.
2. Reduce heat to medium and add the remaining 1 tablespoon oil and onion to the pan. Cook, stirring occasionally, until the onion is softened and lightly browned, about 3 minutes.
3. Whisk broth, vinegar, lemon zest, lemon juice, brown sugar, thyme and the remaining 1/4 teaspoon each salt and pepper in a small bowl. Add the broth mixture to the pan; cook for 30 seconds, stirring and scraping to loosen browned bits from the bottom of the pan. Return the chicken and any accumulated juices to the pan. Partially cover and cook, turning occasionally, until the liquid has reduced and an instant-read thermometer inserted in the thickest part without touching bone registers 165°F, 10 to 15 minutes. Transfer the chicken to a serving plate. Stir butter into the sauce. Serve the sauce over the chicken.