- Preheat your oven to 350°F (175°C). Grease a 9x13-inch baking dish with cooking spray or butter. 
- In a large bowl, combine the thawed hash browns, half of the cheddar cheese, and the diced ham or bacon. Mix well and spread the mixture evenly in the prepared baking dish. 
- In another bowl, whisk together the eggs, milk, garlic powder, onion powder, salt, and pepper until well combined. 
- Pour the egg mixture over the hash brown mixture in the baking dish, ensuring it is evenly distributed. 
- Sprinkle the remaining cheddar cheese on top. 
- Bake in the preheated oven for 45-50 minutes, or until the eggs are set and the top is golden brown. 
- Let the casserole cool for 5-10 minutes before slicing. Garnish with chopped chives if desired.