1 pound package frozen hash brown potatoes, thawed to room temperature*
1/2 cup (1 stick) butter, melted
1 (10.75-ounce) can condensed cream of mushroom soup
1 (8-ounce) container sour cream
1/2 cup chopped onions
2 cups shredded Cheddar cheese
1 teaspoon salt
1/4 teaspoon pepper
2 cups crushed cornflakes
1/2 cup (1/2 stick) butter, melted
Preheat oven to 350 degrees F.
In a large bowl, combine hash browns, 1/2 cup melted butter, soup (don't add water!), onion, cheese, salt, and pepper. Mix well and spread in a 9x13 baking pan.
Saute cornflake crumbs in 1/4 cup melter butter over medium heat. Sprinkle the crumbs over the top of the casserole.
Bake for 40 minutes.