Scalloped Potatoes

Do you like scalloped potatoes? This recipe is one I've used since we first got married. It's sauce is like a gravy made on the stove top, then poured over the sliced potatoes. I got this recipe from a Better Homes and Gardens cookbook.

1/4 cup chopped onion
1/4 cup butter or margarine
1/4 cup flour
2 1/2 cups milk
5 large potatoes, peeled and thinly sliced (equalling 5 cups)
1 1/2 tsp. salt
1/8 tsp. pepper

To make sauce, cook onion in butter or margarine till tender but not brown. Stir in flour, 1 1/2 t. salt, and 1/8 teaspoon pepper. Add milk. Cook and stir till thickened and bubbly. Cook and stir 1 to 2 minutes more. Remove from heat. Place half of the potatoes in a greased 2 quart casserole dish. Cover with half of the sauce. Repeat layers. Bake, covered, in a 350 degree oven for 45 minutes, stirring once. Uncover and bake 30 minutes more, or until potatoes are done. Makes 4 to 6 servings.