1. Preheat the Oven and Prepare the Potatoes:
- Preheat your oven to 350°F (175°C). Peel and thinly slice the potatoes, about 1/8 inch thick. A mandoline slicer can help achieve uniformly thin slices.
2. Make the Sauce:
- In a medium saucepan, melt the butter over medium heat. Stir in the flour to create a roux, cooking for about 1 minute until bubbly but not browned.
- Gradually whisk in the milk until smooth. Continue to cook and stir until the sauce thickens, about 5-7 minutes.
- Season the sauce with salt, pepper, garlic powder, and onion powder. Remove from heat.
3. Layer the Potatoes and Sauce:
- In a greased 9×13 inch baking dish, arrange a layer of sliced potatoes. Pour a portion of the sauce over the potatoes, spreading it evenly. If using, sprinkle a layer of shredded cheddar cheese. Repeat the layers, ending with a layer of sauce on top.
4. Bake:
- Cover the dish with aluminum foil and bake in the preheated oven for about 1 hour.
- After 1 hour, remove the foil, sprinkle the grated Parmesan cheese on top, and continue to bake, uncovered, for an additional 20-30 minutes, or until the top is golden brown and the potatoes are tender.
5. Garnish and Serve:
- Let the scalloped potatoes rest for about 10 minutes before serving. Garnish with chopped fresh thyme or parsley if desired.
Tips:
- Slicing Potatoes: Ensure the potatoes are sliced uniformly to promote even cooking.
- Sauce Consistency: The sauce should be smooth and thick enough to coat the back of a spoon. If it’s too thick, you can add a little more milk; if too thin, cook a bit longer.
- Variations: Feel free to customize your scalloped potatoes by adding layers of sautéed onions, crumbled bacon, or different types of cheese according to your preference.
- Reheating: Scalloped potatoes reheat well in the oven or microwave, making them a great make-ahead dish.
Enjoy your homemade Scalloped Potatoes, a creamy, cheesy, and utterly comforting side dish that pairs wonderfully with a variety of mains, from roasted meats to grilled vegetables.