Instructions:

1. Preheat the Oven: Preheat your oven to 375°F (190°C). Grease a baking dish with butter or non-stick cooking spray.
2. Prepare the Potatoes: Wash and peel the potatoes if desired. Slice them thinly, aiming for uniform thickness to ensure even cooking.
3. Make the Cheese Sauce: In a saucepan over medium heat, melt the butter. Stir in the flour to create a roux, cooking for about 1-2 minutes until it turns golden brown. Gradually whisk in the milk to avoid lumps. Continue whisking until the mixture thickens.
4. Add Cheese and Seasonings: Reduce the heat to low, then add the shredded cheese to the milk mixture. Stir until the cheese is completely melted. Season the sauce with salt, black pepper, and garlic powder if using.
5. Layer the Potatoes: Arrange a layer of thinly sliced potatoes in the prepared baking dish. Pour a portion of the cheese sauce over the potatoes, ensuring they are well-coated. Repeat the process until all potatoes and cheese sauce are used, finishing with a layer of cheese on top.
6. Bake: Cover the baking dish with aluminum foil and bake in the preheated oven for about 45-50 minutes. Uncover for the last 10-15 minutes to allow the top to brown and crisp.
7. Garnish and Serve: Once the potatoes are tender and the top is golden, remove from the oven. Garnish with chopped fresh parsley if desired.
8. Let it Rest: Allow the Cheesy Scalloped Potatoes to rest for a few minutes before serving to let the flavors meld.
9. Serve and Enjoy: Spoon out generous servings of this creamy, cheesy goodness to accompany your main course.

Note: Feel free to customize by adding diced onions, minced garlic, or your favorite herbs for extra flavor.