peeled, thinly sliced
Salt and pepper
Preheat oven to 425 degrees.
Grease a 9-x13-inch baking dish.
Arrange 1/3 of the potatoes in bottom of baking dish.
Sprinkle potatoes generously with salt, pepper, and 3 tablespoons flour; dot with 2 tablespoons butter.
Repeat layering 2 more times, until all potatoes are used.
Slowly pour milk over potatoes. (To make sure flour on the top layer gets moistened, press down gently on potatoes with a spatula to submerge.)
Bake uncovered until milk comes to a boil, about 25 minutes; reduce heat to 375 degrees and bake until potatoes are tender, about 40 minutes.
Let rest for 10 minutes before serving. Leftovers reheat well, covered at 350 degrees for 15 minutes.
If desired, you can add cheese or other spices to layers.