Ingredients:

• 6-8 large potatoes, thinly sliced (with or without skins)
• 1 medium onion, sliced into thin rings
• 3 tablespoons butter
• 4 tablespoons flour
• 1 teaspoon salt
• 1/2 teaspoon pepper
• 3 cups whole milk or fat-free half and half

Directions:

1. Preheat the oven to 400°F. Grease a 9″x13″ casserole dish with butter and set aside.
2. While you prepare the rest of the recipe, allow the potato slices to sit in a large mixing bowl filled with cold water. It’s important not to skip this step – keeping the potatoes in water while preparing the rest of the recipe will prevent them from turning brown from air exposure. This will also remove any excess starch.
3. In a medium saucepan over medium heat, melt the butter. Add the onions to the pot and cook for about 5 minutes until softened.
4. Add the flour, salt and pepper to the pot and combine with the butter mixture using a whisk.
5. Cook for about 2-3 minutes or until everything thickens up. You may need to increase the heat a little. Also make sure you continually whisk so nothing sticks to the bottom of the pan.
6. Once the contents of the pot of cooked and thicken up a bit, pour the milk into the pot. Increase the heat to high, and bring the contents to just a boil. Lower the heat and  whisk as it cooks for about 10-12 minutes more. The milk mixture should thicken.
7. Layer half of the potato slices into the casserole dish and top with half of the cream sauce.
8. Layer the remaining potatoes and top with the remaining cream sauce.
9. Place into the oven to bake uncovered for 45 minutes to 1 hour.
10. The top should become golden brown and the potatoes  should be fork tender.
11. Allow the dish to rest for 5 minutes before serving.