Preheat the oven to 350°F (175°C).
In a large bowl, combine the shredded chicken, crumbled bacon, diced potatoes, ranch dressing, sour cream, garlic powder, salt, and pepper, mixing well until everything is combined.
Transfer the mixture into a greased 9x13 inch baking dish, spreading it evenly.
Sprinkle shredded cheddar cheese evenly over the top of the casserole.
Cover the dish with aluminum foil and bake in the preheated oven for 30 minutes.
Remove the foil and bake for an additional 15-20 minutes, or until the cheese is bubbly and golden brown.
Let the casserole cool for a few minutes before serving.