Preheat the oven to 375 degrees F. Butter/Grease a 9 x 13-inch casserole dish or 12-inch Dutch oven.
In a medium bowl, mix together the soup, sour cream, cream cheese and egg.
Stir in the hash browns, butter, 1 cup of cheese, onion and bacon.
Scrape the mixture into the prepared baking dish. Sprinkle the top with the remaining 1 cup of cheese. Bake for about 45 minutes, or until bubbling throughout and the top is lightly browned. Let cool slightly, cut and serve warm.