Preheat oven to 400 degrees F. Spray a 9x13-inch baking dish with nonstick cooking spray; set aside.
Melt butter in a large skillet over medium-high heat. Add chicken and cook 2-3 minutes on each side just until browned. Transfer chicken to prepared pan.
In a small bowl, whisk together chicken broth, minced garlic, lemon juice, thyme, salt and pepper and pour over chicken. Top chicken with lemon slices and rosemary.
Bake for 20-30 minutes, or until it reaches an internal temperature of 165 degrees F.