Preheat oven at 350 and grease a 2 quart casserole.Melt 2 T margarine, stir in flour, salt, pepper and blend until smooth.Slowly stir in milk, and stir until thickened.Add hash browns, eggs then stir to combine.Melt remaining margarine and combine with 'cornflakes' crumbs and sprinkle on top.Bake uncovered 30 minutes or until hot and bubbly.