Pat chicken thighs dry with a paper towel or kitchen towel on both sides.
Season one side with half of the salt, pepper, and garlic powder.
Heat large skillet over medium heat for several minutes until hot. Add oil.
Place chicken thighs seasoned side down in the hot skillet and cook for 3-4 minutes until well browned on one side.
Season the second side, flip and continue to cook for another 3-4 minutes.
When browned on both sides, check for doneness with an instant read thermometer. You are looking for an internal temperature of 165 degrees F in the thickest part of the meat.
If chicken is not done, lower the heat and cover with a lid and continue to cook for another few minutes until chicken has cooked through.
Remove chicken from the skillet and set aside to rest on a plate.
If making the pan sauce, remove all but a small portion of the excess fat.
Add chicken stock and whisk, taking care to scrape up the brown bits on the bottom of the pan.
Add thyme and rosemary and continue simmering sauce for about 3 minutes or until it has reduced by about a third.
Whisk in butter, taste and adjust seasonings if needed, and pour over chicken thighs.