To a 9x13 or similar casserole dish, add butter and pop into the preheating oven to melt, about 2-3 minutes. Remove from the oven. Add chicken and sprinkle with poultry seasoning, onion powder, pepper, and vegetables.
In a measuring cup or medium bowl, combine biscuit mix and milk (and seasoning packet if there is one). It’s OK if there are lumps. Pour over chicken and vegetables. Do not mix.
In a measuring cup or medium bowl, whisk together chicken broth and soup until smooth. Gently pour over biscuit mix. Do not mix. Sprinkle with 1 teaspoon parsley if desired.
Bake uncovered for 45-50 minutes or until top is golden brown. It’ll be slightly jiggly in the center. Baking it 50 minutes will mean it is a little less saucy. Allow to rest 10-15 minutes before serving to set. Garnish with parsley if desired and serve.