Preheat the Oven
Preheat your oven to 375°F (190°C). Take a 9x13 inch baking dish and grease it thoroughly to prevent sticking. This preparation ensures even cooking and easy serving once the casserole is done.
Create the Creamy Base
In a large mixing bowl, combine the shredded chicken, cream of chicken soup, sour cream, shredded cheddar cheese, milk, garlic powder, and black pepper. Mix thoroughly until all ingredients are well incorporated and evenly distributed, forming a creamy, consistent mixture.
Prepare the Biscuits
Take the refrigerated biscuits and cut each one into quarters. Gently fold these biscuit pieces into the chicken mixture, being careful not to overmix or break them down too much. The biscuits should be coated but still maintain their shape.
Assemble the Casserole
Transfer the entire mixture to your greased baking dish, spreading it out evenly. Pour the melted butter uniformly over the top of the casserole. This will help the biscuits achieve a golden, crispy exterior while baking.
Bake to Perfection
Place the baking dish in the preheated oven and bake for 35-40 minutes. The casserole is done when the top is golden brown and the biscuits are completely cooked through. You can test by inserting a toothpick into a biscuit piece - it should come out clean.