Ingredients

• 3 pounds russet potatoes , thinly sliced
• ½ onion , thinly sliced
• 9 tablespoons all-purpose flour , divided
• 6 tablespoons butter , cubed and divided
• salt and ground black pepper to taste
• 3 cups whole milk , or as needed

Instructions

1. 1 Gather the ingredients. Preheat the oven to 375 degrees F (190 degrees C). Grease a 9x13-inch baking dish.
2. 2 Spread about 1/3 of the potato slices into the bottom of the prepared baking dish. Top with about 1/3 of the onion slices. Sprinkle 3 tablespoons flour over the potato and onion. Arrange 2 tablespoons cubed butter atop the flour. Season the entire layer with salt and pepper. Repeat layering twice more.
3. 3 Heat milk in a saucepan over medium-low heat until warm. Pour enough warm milk over mixture in the baking dish so the top of the liquid is level with the final layer of potatoes.
4. 4 Bake in the preheated oven until potatoes are tender and the creamy sauce is bubbling with a golden brown crust, 45 to 60 minutes. The cream sauce may bubble up over the sides of the baking dish; place a baking sheet underneath to catch any drips. Serve hot and enjoy!

Nutrition per serving