Preheat the oven to 350℉. Spray a 9x13-inch baking dish with cooking spray. Set aside.
In a large bowl, combine the frozen diced hash brown potatoes, diced ham, shredded cheddar cheese, and finely diced sweet onion. Stir until evenly mixed.
1 bag (32 oz) frozen diced hash browns, 2 cups diced pre-cooked ham, 2 cups shredded mild cheddar cheese, 1 sweet onion
In a separate smaller bowl, whisk together the cream of chicken soup, sour cream, melted butter, garlic powder, kosher salt, black pepper, and onion powder until smooth and combined.
1 can (10.5 oz) cream of chicken soup, 1 cup sour cream, 1/2 cup (1 stick) butter, 1 teaspoon garlic powder, 1 teaspoon kosher salt, ½ teaspoon black pepper, ½ teaspoon onion powder
Pour the soup mixture over the hash brown mixture in the larger mixing bowl. Stir everything together until well-coated.
Transfer the potato mixture to the baking dish, spreading it out evenly. Cover the casserole with aluminum foil and bake for 1 hour.
Remove the foil from the pan and bake an additional 15 minutes or until the casserole is golden brown and bubbly on top and the internal temperature reaches 165℉.
Serve hot and enjoy!