Ingredients
4 russet potatoes, sliced into 1/8 inch slices
1 onion, sliced into rings
3 tablespoons butter
3 tablespoons all-purpose flour
1/2 teaspoon salt
1 1/2 cups milk
1 cup sour cream
2 1/2 cups shredded Cheddar cheese
Directions
1. Preheat oven to 400F. Butter a 1 quart casserole dish.
2. In a medium-size saucepan, melt butter over medium heat. Mix in the flour and salt, and stir constantly with a whisk for one minute. Stir in milk and sour cream. Cook until mixture has thickened. Stir in cheese all at once, and continue stirring until melted, about 30 to 60 seconds.
3. Layer 1/2 of the potatoes into bottom of the prepared casserole dish. Top with the onion slices and out half of the sauce over the potatoes. Add the remaining potatoes. Season with salt and pepper to taste and pour remaining cheese over the potatoes. Sprinkle remaining 1/2 cup of Cheddar cheese over the top.
4. Cover the dish with aluminum foil and bake for 1 1/2 hours in the preheated oven.