First, grease a 9x13 baking dish.
Then spread frozen hash browns evenly on the bottom.
Cook the sausage, drain the grease, and crumble it over the hash browns.
Add 1 cup of cheese on top of the sausage.
Whisk eggs, milk, sour cream, salt, pepper, onion powder, and garlic powder.
Pour the egg mixture over everything.
Top with the remaining cheese.
Cover with foil.
Refrigerate overnight or bake immediately.
Bake at 350°F for 45 minutes covered.
Remove foil, bake 15 more minutes till golden.
Let rest 5-10 minutes.
Top with green onions and serve.