Preheat oven to 375 degrees F (190 degrees C). Lightly grease a 9x13 inch baking dish.

In a large skillet over medium heat, fry bacon pieces until crisp; remove to paper towels. Reserve half of bacon drippings, and set aside. Return skillet to stove; stir onions, and cook until soft and translucent.

In a large bowl, stir together reserved drippings, bacon, onion, and potatoes. Mix in flour, evaporated milk, and eggs. Season with salt and pepper to taste.

Pour into baking dish, and bake in a preheated oven until top is nicely brown, about 1 hour. Cut into squares, and serve with sour cream, if desired.