Hash Brown Chicken

1 (32 ounce) package frozen hash brown potatoes, thawed
2 cups cut-up cooked chicken
1 cup melted margarine, divided
1 (10 3/4 ounce) can cream of mushroom soup
8 ounces shredded cheddar cheese
1 small onion, chopped
1 (8 ounce) container sour cream
2 cups crushed cornflakes

Heat oven to 350 degrees F.

Combine hash browns and chicken in an ungreased 13 x 9 x 2-inch baking dish.

Mix together 1/2 cup margarine, mushroom soup, cheese, onion and sour cream. Pour over potatoes and chicken. Top with cornflakes. Drizzle remaining 1/2 cup margarine over top. Bake uncovered 45 minutes.