Description
Potatoes au Gratin is a classic French dish featuring thinly sliced russet potatoes baked in a rich and creamy cheddar cheese sauce, layered with onions for added sweetness and depth of flavor. This comforting casserole offers a golden, bubbly crust with tender, cheesy potatoes underneath, perfect as a hearty side or a satisfying main.
Ingredients
Scale
Potatoes and Vegetables
- 6 medium russet potatoes, thinly sliced
- 1 medium onion, sliced
Sauce
- 3 tablespoons butter
- 3 tablespoons all-purpose flour
- 2 cups milk
- 1/2 teaspoon salt
- 1/2 teaspoon black pepper, to taste
- 1 ½ cups shredded Cheddar cheese
Instructions
- Prepare Baking Dish: Preheat your oven to 400℉ and grease a 9×13-inch baking dish thoroughly to prevent sticking and ensure easy serving.
- Layer Potatoes and Onions: Arrange half of the thinly sliced potatoes evenly at the bottom of the casserole dish. Spread the sliced onions over the potatoes, then layer the remaining potatoes on top, creating a sturdy base for the cheese sauce.
- Make Roux: In a large skillet over medium heat, melt the butter. Add the flour and cook, stirring constantly for 1-2 minutes until the mixture turns a light golden color, which cooks out the raw flour taste.
- Prepare Cheese Sauce: Gradually whisk in the milk, salt, and black pepper to the roux. Continue stirring until the sauce reaches a boil, then cook for an additional minute to thicken. Remove from heat and stir in the shredded Cheddar cheese until fully melted and smooth.
- Assemble and Bake: Pour the warm cheese sauce evenly over the layered potatoes and onions in the baking dish. Cover the dish tightly with foil and bake in the preheated oven for 50-60 minutes. Remove the foil and bake for a further 15-20 minutes until the top is golden brown and bubbly.
Notes
- For easier slicing, use a mandoline to get consistently thin potato slices.
- Russet potatoes work best for their starchy texture, which softens nicely during baking.
- Add garlic powder or fresh minced garlic to the cheese sauce for extra flavor.
- Let the dish rest for 10 minutes before serving to allow it to set and make slicing easier.
- Leftovers can be stored in the refrigerator for up to 3 days and reheated in the oven.
