Season the chicken with salt, pepper, garlic powder, thyme, and parsley.
Place the chicken in the bottom of the crockpot.
Add the onion, carrots, celery, and garlic.
Whisk together the chicken broth and cream of chicken soup, then pour over the chicken and vegetables.
Cover and cook on LOW for 5–6 hours or HIGH for 3–4 hours, until the chicken is tender and cooked through.
Remove the chicken and shred it with two forks.
Return the shredded chicken to the crockpot.
Stir in the cream or milk and frozen peas.
Make the dumplings by combining flour, baking powder, and salt in a bowl. Stir in milk and melted butter until a soft dough forms.
Drop spoonfuls of dough over the chicken mixture.
Cover and cook on HIGH for 30–45 minutes, until the dumplings are fluffy and cooked through.
Garnish with fresh parsley and serve warm.