Cook bacon until crispy before adding — raw bacon steams under foil and stays soft. Reserve a little bacon and a quarter cup of cheese for the top after the foil comes off. Even potato pieces are important — uneven pieces mean uneven cooking. Make ahead: assemble, cover, refrigerate up to 24 hours; add 10-15 minutes to covered bake time. Leftovers fried in a cast iron skillet with butter become excellent breakfast potatoes.