Preheat oven to 350°. Spray a 9'"x13" casserole dish with cooking spray.
Cut sausage links into small pieces and chop onions
In a large bowl, mix together 1 cup cheese, sour cream, onion, melted butter, salt and pepper. Add sausage and hash browns, gently toss to combine. Pour into prepared casserole dish and top with remaining 1/2 cup cheese.
Bake for 45 minutes or until heated through and just starting to brown. Let sit 5 minutes before serving.