hash brown casserole recipe

### Ingredients: - **2 pounds** frozen hash browns, thawed - **1/2 cup** unsalted butter, melted - **1 can** (10.5 ounces) condensed cream of chicken soup - **1 pint** sour cream - **1/2 cup** chopped onion - **2 cups** shredded cheddar cheese - **1 teaspoon** salt - **1/2 teaspoon** black pepper - **1/2 cup** crushed cornflakes (optional, for topping) - **2 tablespoons** melted butter (optional, for topping)