Begin by layering your ingredients in the slow cooker. Place the chicken thighs at the bottom, then add the chopped carrots, diced celery, and chopped onion.

In a separate bowl, combine chicken stock, au jus mix, chicken gravy mix, garlic powder, onion powder, and black pepper. Whisk until well blended.

Pour the whisked broth mixture over the chicken and vegetables in the slow cooker, ensuring everything is evenly coated.

Cover the slow cooker and set it to cook on low for 6 hours or high for 4 hours.

Check that the chicken and vegetables are tender and easily forked apart. If not, cook for another 30 minutes on low.

Ladle the chicken and vegetables onto plates, spooning gravy over the top, and garnish with fresh parsley.