01 -
Preheat the oven to 175°C (350°F). Grease an 8-inch square pan and add the thawed hash brown potatoes in an even layer.
02 -
Place the sausage and diced onion in a large skillet over medium heat. Cook, stirring occasionally, until the sausage is browned and crumbled, approximately 10 minutes. Drain any excess fat.
03 -
In a large bowl, whisk together the eggs, milk, onion powder, garlic powder, salt, and ground black pepper until well combined.
04 -
Pour the egg mixture over the potatoes in the baking dish and sprinkle with half of the shredded Cheddar cheese. Add the cooked sausage and onion mixture on top and cover with the remaining Cheddar cheese. Cover the baking dish with aluminum foil.
05 -
Bake the casserole in the preheated oven for 1 hour. Remove the foil, then return the casserole to the oven and bake for an additional 10 minutes, or until a knife inserted into the center comes out clean.
06 -
Let the casserole stand for 5 minutes before serving.