Preheat oven to 350°.
In a large skillet, cook bacon until crisp but not burned. Remove with a slotted spoon to paper towels to drain and cool.
Remove all but a tablespoon of the bacon fat from the skillet and saute the mushrooms and onions until tender. Allow to cool slightly.
In a large bowl, mix the beef, egg, and milk. Add the mushroom/onion mixture, all but a few spoonfuls of the Swiss cheese and all but one tablespoons of the bacon bits. Add the corn flake crumbs and mix well until blended.
Shape into a loaf and place in a large loaf pan. Bake at 350 for about an hour, or until cooked through. Drain fat from the pan and sprinkle the reserved cheese and bacon on top. Bake an additional 5 minutes, or until cheese is bubbly. Allow to rest for 10 minutes before slicing.
Please Note: Nutritional values listed may vary from final results depending on actual measurements and brands used to prepare the recipe.