Place chopped onions on the bottom of the crock pot.
Lay chicken on top of the chopped onions in a single layer.
In a medium mixing bowl, add the cans of Cream of Chicken and Cream of Celery soup into the mixing bowl; mix to thoroughly combine.
Adding 1 tsp. poultry seasoning to the mixing bowl; sprinkle with 2 tbsp. freshly chopped parsley; add black pepper, to taste; mix to thoroughly combine.
Pour mixture over chicken in the crock pot.
Pour two cups of chicken broth over the chicken.
Set the crock pot on high for 5 hours; place the cover on the crock pot and do not open until 1 hour of cooking time remains on the display.
When only 1 hour cooking time remaining, remove the cover; pour in 2 cups thawed mixed vegetables.
Stir contents while breaking up the chicken pieces.
Open the package of Pillsbury butter biscuits; flatten each piece and cut each into 4 quarters.
Add biscuits to the pot; cook for about 8 to 9 minutes.
Test one of the biscuits to ensure they have cooked through and are not raw in the middle.
Once the biscuits are cooked through, serve immediately.
