My great-grandparents immigrated from Lithuania in the early 20th century and brought with them this potato recipe that I have been eating my whole life. My grandfather actually had to teach my grandmother to make it, who in turn taught my mother and my mother taught me. Definitly an heirloom recipe.
Cook bacon until crispy. Set aside to cool and let the bacon fat cool as well. When bacon is cool, chop finely in food processor.
Pre-heat oven to 400 degrees. Beat eggs, milk, salt and pepper as well as the reserved bacon fat. Add bacon and mix well.
Peeled potatoes should be shredded as the last step to keep them from turning color. Shred onion with the potato. Mix potatoes/onion with the egg mixture completely and pour into a greased baking dish. (I used a 10 x 15.)
Bake and test for doneness at 1 hour. Like a cake, it will pull from the sides of the pan and a knife should come out clean.
Slice and serve with sour cream on top. This can also be sliced thin and fried with butter as a side with eggs for breakfast.