In a large bowl mix, hash browns, onion,cheese,sour cream,and the 2 cans of soup. Melt 1/2 stick of butter and cream cheese. Pour this mixture over hash brown mixture and mix well. Once mixed pour into a greased 9x13 pan. Crush corn flakes and mix with other 1/2 stick of butter and pour on top. Bake at 300 for 1 hour and 20 minutes.