Preheat the Oven: Start by preheating your oven to 375°F.
Prepare the Filling: In a large skillet, melt the butter over medium heat. Stir in the onions and garlic, sautéing until fragrant. Sprinkle in the flour and cook for about 2 minutes, stirring continuously to eliminate any raw flour taste.
Create the Sauce: Gradually whisk in the chicken broth, making sure to avoid any lumps. As the mixture begins to thicken, add the half and half, cream of chicken soup along with seasoning. Allow the sauce to simmer for 5 minutes, then stir in the cooked chicken and vegetables. Cook until the vegetables are tender.
Assemble the Pot Pie: Pour the chicken filling into a 9x13-inch baking dish. Drop bisuit over the filling, following box instructions, spreading it evenly across the dish.
Bake: Place the dish in the preheated oven and bake for 30-40 minutes, or until the biscuits are golden brown and fully cooked.
Finish and Serve: Once baked, brush the tops of the biscuits with the packaged seasoning and melted butter and sprinkle with chopped parsley. Serve hot and enjoy the warm, cheesy, and savory flavors of this Cheddar Bay Biscuit Pot Pie.