This is amazing! I could eat it every day and never get tired of it.

Heat your oven to 350°F (175°C) and grease a baking dish that measures 9 by 13 inches.
In a big bowl, mix together the defrosted shredded potatoes, cooked sausage, and chopped onion.
In another bowl, combine the sour cream, creamy chicken soup, cheddar cheese, and melted butter until mixed well.
Pour the creamy mixture over the shredded potato mixture and mix well until everything is covered evenly. Add salt and pepper according to your preference.
Spread the mix evenly in the baking dish that has been prepared. If you want, add crushed cornflakes on top.
Cook in the oven for 45 minutes to 1 hour, or until it is bubbling and has a golden brown top.
Allow to cool a bit before serving.