Place the chicken thighs in the bottom of a 6-quart crockpot.
Scatter the diced onion, carrots, and celery around the chicken.
In a medium bowl, whisk together the cream of mushroom (or cream of chicken) soup, chicken broth, garlic powder, thyme, rosemary, black pepper, and salt.
Pour the gravy mixture over the chicken and vegetables, making sure everything is evenly coated.
Cover the crockpot and cook on low for 6-8 hours, or until the chicken is tender and the gravy is thickened.
Once the cooking time is up, use two forks to shred the chicken directly in the crockpot.
Taste the gravy and adjust the seasoning as needed, adding more salt, pepper, or herbs to your preference.
Serve the crockpot chicken and gravy over mashed potatoes, rice, or egg noodles. Garnish with fresh parsley or chives, if desired.