Preheat oven to 350.
In a large mixing bowl, add hashbrowns, 1/2 c melted butter, soup, sour cream, cheese, salt, and pepper. Stir until everything is blended well.
Pour into a lightly greased 9x13" pan and bake in preheated oven for 30 minutes.
While casserole is baking, saute crushed cornflakes in remaining butter (1/4 c) in a pan on the stove top over medium heat for about 5 minutes.
Once the casserole has baked for 30 minutes, remove from oven and spread sauteed cornflakes evenly on the top.
Put the casserole back in the oven for 10 more minutes.
Remove from oven, allow to cool slightly, and serve it as a delicious side dish!