Potatoes Au Gratin

Ingredients:

• 4 medium russet potatoes, thinly sliced
• 1 medium onion, sliced into rings
• Salt & black pepper, to taste
• 3 tbsp butter
• 3 tbsp all-purpose flour
• ½ tsp salt
• 2 cups milk
• 1 ½ cups shredded cheddar cheese

Instructions:

1. Preheat oven to 400°F (200°C) and grease a 2-quart casserole dish with butter.
2. Layer half of the sliced potatoes in the dish; season with salt and pepper. Add the onion slices, then layer the remaining potatoes. Season again.
3. In a saucepan over medium heat, melt the butter. Whisk in flour and ½ tsp salt; cook for 1 minute.
4. Slowly pour in the milk, whisking constantly to avoid lumps. Cook until thickened, 3–5 minutes.
5. Stir in the cheddar cheese until melted.
6. Pour the cheese sauce evenly over the potatoes. Cover with foil.
7. Bake for about 1 hour 30 minutes, until potatoes are tender and sauce is bubbly.