Preheat your oven to 350°F (175°C) and lightly grease an 8-inch square baking pan.

Spread the thawed hash brown potatoes evenly into the greased baking pan, pressing them down.

In a large skillet over medium heat, cook the pork sausage with the diced onion until browned and translucent, about 10 minutes.

In a mixing bowl, whisk together the eggs, milk, onion powder, garlic powder, salt, and pepper until well blended.

Pour the egg mixture over the hash browns in the baking pan and spread it out. Sprinkle half of the cheddar cheese on top.

Add the cooked sausage and onion mixture on top of the cheese layer, then add the remaining cheese.

Cover with aluminum foil and bake for 1 hour. Remove foil and bake an additional 10-15 minutes until golden and bubbly.

Remove from oven and let it rest for about 5 minutes before serving.