6 medium potatoes, peeled and thinly sliced
4 tablespoons butter
3 tablespoons flour
1 teaspoon salt
1/4 teaspoon pepper
2 1/2 cups milk
1 small onion, finely chopped
Preheat oven to 325ºF.
Heat 3 tablespoons of butter in a saucepan over low heat until melted. Blend in flour, salt and pepper. Cook over low heat, stirring constantly, until mixture is smooth and bubbly. Gradually stir in milk, 1/2 cup at a time. Heat to boiling. Boil and stir 1 minute.
Arrange potatoes in greased 2 quart casserole in 3 layers, topping each layer with part of the chopped onions and 1/3 of the sauce. Dot the top with the remaining 1 tablespoon of butter, broken into little pieces.
Cover and bake until potatoes are tender, about 60-70 minutes. Let stand 5 to 10 minute before serving.
I used the above recipe to go with a lovely big roast ham. It was superb.