Scalloped Potatoes

Gather the ingredients. Preheat the oven to 375 degrees F (190 degrees C). Grease a 9x13-inch baking dish.

Arrange about ⅓ potato slices in the bottom of the prepared baking dish; top with about ⅓ onion slices. Sprinkle 3 tablespoons flour over potato and onion layer; place 2 tablespoons cubed butter on top. Season layer with salt and black pepper. Repeat layering twice more.

Heat milk in a saucepan over medium-low heat until warm. Pour enough warm milk over mixture in the baking dish until top of the liquid is level with the final layer of potatoes.

Bake in the preheated oven until potatoes are tender and sauce is bubbling with a golden brown crust, 45 to 60 minutes. Place a baking sheet underneath the baking dish to catch any drips; the sauce may bubble up over the sides. Serve hot and enjoy!