Preheat your oven to 350°F (175°C).
In a large mixing bowl, combine the frozen hashbrowns, diced bell peppers, diced onions, garlic powder, salt, and black pepper.
In a separate bowl, whisk together the eggs and milk until well combined.
Pour the egg mixture over the hashbrown mixture and stir gently to combine.
Sprinkle the shredded cheddar cheese evenly on top of the mixture.
Transfer the mixture to a greased 9x13-inch baking dish.
Bake in the preheated oven for 45–50 minutes, or until the eggs are set and the top is golden brown.
Allow the casserole to rest for 10 minutes before serving.
