Place the frozen hash browns and onions in a casserole dish and season with seasoned salt or salt and pepper.
Place the sausage evenly over the hash browns and pour the eggs over top. Sprinkle the whole dish evenly with cheese and cover with foil. Refrigerate overnight.
In the morning preheat the oven to 375 degrees and bake the casserole, covered for one hour. Take the foil off and continue baking for another 10-15 minutes.
Let the casserole sit for 10 minutes before slicing.
Recipe by Friday is Cake Night at https://www.fridaycakenight.com/2015/12/overnight-hash-brown-casserole/