Scalloped Potatoes

Instructions:

1. Preheat your oven to 400°F (200°C). Prepare an 8x8-inch (20x20 cm) casserole dish by lightly spraying it with nonstick cooking spray.

2. Begin layering the dish by arranging the peeled and sliced potatoes and sliced onions, alternating between potato slices and onion rings, until the dish is filled.

3. In a medium saucepan, melt the unsalted butter over medium heat. Once melted, whisk in the all-purpose flour, kosher salt, and black pepper. Stir continuously for one minute to form a roux.

4. Gradually stir in the whole milk to the roux, ensuring continuous stirring to incorporate the milk smoothly without lumps. Continue to cook and stir until the mixture thickens to a sauce-like consistency.

5. Add 100g of both medium and sharp cheddar cheeses designated for the sauce into the milk mixture. Stir until the cheeses are fully melted and the sauce is smooth and creamy.

6. Evenly pour the cheese sauce over the arranged potatoes and onions in the casserole dish. Ensure the sauce covers all the potatoes and onions.

7. Cover the casserole dish with aluminum foil and bake in the preheated oven for 90-95 minutes, or until the potatoes are tender when pierced with a fork.

8. Once the potatoes are tender, remove the dish from the oven and uncover it. Sprinkle the top evenly with the remaining 50g of sharp cheddar and 50g of medium cheddar cheese designated for topping.

9. Place the dish back in the oven, uncovered, for a few minutes just until the cheese topping has melted and is bubbly.

10. Serve the potato and onion casserole hot, straight from the oven, as a comforting and cheesy side dish. Enjoy your meal!