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Au Gratin Potatoes Recipe

Golden, cheesy, and irresistibly creamy, these au gratin potatoes are the ultimate comfort food. Thinly sliced potatoes are layered with onions, bathed in a velvety cheese sauce, and baked to bubbly perfection. Perfect for holidays or weeknight dinners, this dish pairs beautifully with roasted meats or vegetables.
Prep Time 30 minutes
Cook Time 1 hour 30 minutes
Total Time 2 hours
Course Side Dish
Cuisine French
Servings 4 people
Calories 499 kcal

Equipment

  • 2-quart casserole dish
  • Sharp knife or mandoline slicer
  • Medium saucepan
  • Whisk
  • Measuring cups and spoons
  • Aluminum foil

Ingredients
  

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

Instructions
 

  • Preheat the oven to 400°F (200°C) and butter a 2-quart casserole dish.
  • Arrange half of the sliced potatoes in the dish, season with salt and pepper, then layer the onion slices on top.
  • Add the remaining potatoes and season again.
  • In a saucepan over medium heat, melt the butter, whisk in flour and salt, and cook for about a minute until the raw flour taste is gone.
  • Slowly add milk, about ¼ cup at a time, whisking constantly to prevent lumps.
  • Cook until thickened, 3 to 5 minutes, then stir in the cheese until fully melted.
  • Pour the cheese sauce over the layered potatoes, ensuring even coverage.
  • Cover with aluminum foil and bake for about 1 ½ hours, until the potatoes are tender and the sauce is bubbling.
  • Serve hot and enjoy.

Notes

  • For even cooking, slice the potatoes no thicker than ¼ inch. A mandoline slicer ensures uniform slices.
  • For extra richness, substitute half of the milk with heavy cream.
  • Try using a mix of cheeses, like Gruyère and sharp cheddar, for added depth of flavor.