In a large bowl combine the onion, 1 cup of cheese, milk, cream of chicken soup and sour cream. Stir to combine.
Mix in the hasbhrowns and stir to coat.
Pour into a 9x13 pan. Top with the remaining cheese.
Cover with foil and bake in the preheated oven for 45-50 minutes.
Remove the foil and bake for 5-10 minutes to brown the the cheese is slightly.
Video
Notes
This casserole can be assembled before hand, covered and store in the refrigerator for 3-4 days. Then bake according to the recipe. *Leftovers can be stored in the refrigerator for up to 5-7 days.