Prepare your ingredients by dicing the onion and celery.
In a bowl, mix the stuffing mix with chicken broth and set aside.
Season the chicken breasts with salt, pepper, and garlic powder.
Place the chicken breasts at the bottom of the crockpot.
Spread the diced onion and celery over the chicken.
In another bowl, combine the cream of chicken soup with dried thyme.
Pour the soup mixture over the chicken and vegetables.
Top with the stuffing mixture, ensuring it's evenly distributed.
Cover the crockpot and cook on low for 6-8 hours or high for 4-5 hours.
Check the chicken for doneness before serving, ensuring it reaches 165°F (75°C).