Scalloped Potatoes

Heat oven to 350°F. Grease 2-quart casserole with shortening or cooking spray.

In 2-quart saucepan, melt 3 tablespoons of the butter over medium heat. Cook onion in butter about 2 minutes, stirring occasionally, until tender. 

Stir in flour, salt, and pepper with a whisk. Cook, stirring constantly, until smooth and bubbly; remove from heat. 

Stir in milk with a whisk. Heat to boiling over medium heat, stirring constantly. Boil and stir 1 minute. Remove from heat; cover and let stand while prepping the potatoes.

Wash the potatoes, and with a vegetable peeler, remove the skins, if desired. Rinse under cool water. Cut the potatoes into thin slices.

Spread potatoes in casserole. Pour sauce evenly over potatoes. Cut remaining 1 tablespoon butter into small pieces; sprinkle over the potatoes and sauce.

Cover with foil; bake 30 minutes. Uncover; bake 1 hour to 1 hour 10 minutes longer or until potatoes are tender when pierced with a fork. Let stand 5 to 10 minutes before serving (sauce thickens as it stands).