2 tablespoons butter
3 tablespoons all-purpose flour
1 teaspoon salt
1/4 teaspoon pepper
1-1/2 cups milk
1/2 cup shredded cheddar cheese
2 pounds red potatoes, peeled and thinly sliced (about 4 cups)
1 cup thinly sliced onions, divided
Directions
Preheat oven to 350°. In a small saucepan, melt butter; stir in flour, salt and pepper until smooth. Gradually whisk in milk. Bring to a boil, stirring constantly; cook and stir until thickened, about 2 minutes. Remove from heat; stir in cheese until melted.
Coat an 8-in. square baking dish with cooking spray. Place half of the potatoes in dish; layer with 1/2 cup onion and half of the cheese sauce. Repeat layers.
Bake, covered, 50 minutes. Uncover; then bake until bubbly and potatoes are tender, 10-15 minutes longer.
