Place the onion in the bottom of a slow cooker.
Add the chicken breasts on top of the onion.
In a mixing bowl, combine the cream of celery soup, cream of chicken soup, chopped parsley, poultry seasoning, oregano, celery flakes and salt and pepper to taste. Mix to combine.
Spread the mixture over the chicken in the slow cooker.
Pour two cups of chicken broth into the slow cooker, place the lid on it, and cook on high for 5 hours.
Remove and shred the chicken before adding it back to the slow cooker.
Sprinkle a bag of frozen mixed vegetables into the slow cooker.
Break the biscuits into dumpling sized pieces and put them into the slow cooker, stir the mixture to combine, place the lid back on and cook on high for an additional hour.
Serve with freshly chopped parsley for garnish if desired.
Enjoy!