Preheat your oven to 375°F (190°C) and grease a baking dish.
Melt butter in a saucepan over medium heat. Whisk in flour and cook for 1-2 minutes until golden.
Gradually add milk, stirring continuously, and simmer until the sauce thickens.
Off the heat, stir in sharp cheddar cheese, salt, and optional cayenne pepper until smooth.
Arrange half of the sliced potatoes in the baking dish. Pour half of the cheese sauce over them.
Layer the remaining potatoes and top with the rest of the sauce.
Sprinkle the top with the extra grated cheese.
Cover with foil and bake for 45 minutes, then uncover and bake for an additional 15-20 minutes until golden and crispy.
Serve hot, garnished with green onions if desired. Each bite of these Scalloped Potatoes will remind you of the comfort and joy of family gatherings. Enjoy this creamy, cheesy masterpiece and let it take you back to those cherished days at grandma’s house.
