Prep Oven & Dish: Preheat your oven to 350°F (175°C).
Combine Ingredients: In a large mixing bowl, combine the shredded chicken, thawed hashbrowns, shredded Cheddar cheese, sour cream, cream of chicken soup, diced onion, and diced bell pepper. Mix well until all the ingredients are evenly combined.
Season & Transfer: Season the mixture with salt and pepper to taste. Transfer the mixture into a greased 9×13-inch baking dish.
Bake: Spread the mixture evenly in the baking dish. Place the baking dish in the preheated oven and bake for 45-50 minutes, or until the casserole is golden brown and bubbling around the edges.
Cool & Serve: Remove the casserole from the oven and let it cool for a few minutes before serving. Serve the Chicken Hashbrown Casserole hot and enjoy!

For a more flavorful casserole, you can add some cooked and crumbled bacon to the mixture before baking.
If you prefer a spicier casserole, you can add some diced jalapeños or a sprinkle of cayenne pepper.
Make sure to thaw the hashbrowns completely before using them in the recipe. This will ensure even cooking and prevent any excess moisture in the casserole.