Preheat oven: Preheat oven to 400°F (200°C).
Prepare baking dish: Place the hashbrowns in the bottom of a 9×13 inch baking dish.
Combine ingredients: In a large bowl, combine the shredded cheddar cheese, frozen peas and carrots, sour cream, drained corn, cream of chicken soup, shredded chicken, milk, and season with salt and pepper to taste. Mix well.
Layer casserole: Pour the combined ingredients over the layer of hashbrowns in the baking dish.
Top with breadcrumbs: Sprinkle the top of the casserole evenly with breadcrumbs.
Bake: Bake for 1 hour, or until the casserole is golden brown and bubbly.
Serve: Let the casserole cool slightly before serving.
Enjoy this warm and satisfying dish!