Classic Potatoes Au Gratin
Experience the ultimate comfort food with this velvety potatoes au gratin. A rich brown-butter roux and sharp cheddar create a deeply flavorful sauce that blankets every tender potato slice.
Equipment
- 2-quart casserole dish
- Medium saucepan
- Whisk
- Mandoline or sharp knife
Ingredients
- 4 medium russet potatoes thinly sliced
- 1 medium onion sliced into rings
- salt and ground black pepper to taste
- 3 tablespoons butter
- 3 tablespoons all-purpose flour
- 1/2 teaspoon salt
- 2 cups milk
- 1 1/2 cups shredded Cheddar cheese
Instructions
Prep the pan and build the layers
- Heat the oven to 400 degrees F (200 degrees C). Butter a 2-quart casserole dish generously to prevent sticking.
- Lay down half of the thinly sliced potatoes in a slightly overlapping layer and season evenly with salt and ground black pepper.
- Scatter the onion rings over the potatoes, then top with the remaining potato slices and another seasoning of salt and pepper.
Brown butter roux, then a smooth milk base
- In a medium saucepan over medium heat, melt the butter and cook until it foams and turns golden with a nutty, toasted aroma.
- Whisk in the all-purpose flour and 1/2 teaspoon salt. Cook for about 1 minute, whisking constantly until the mixture is smooth and smells toasted.
- Pour in the milk gradually, approximately 1/4 cup at a time, whisking vigorously after each addition to ensure a silky texture.
- Continue cooking and whisking constantly for 3 to 5 minutes until the sauce is thick enough to coat the back of a spoon.
Melt the cheese, bake, then let it settle
- Stir in the shredded Cheddar cheese all at once and mix until completely melted and glossy, which takes about 30 to 60 seconds.
- Pour the warm cheese sauce evenly over the layered potatoes and cover the dish tightly with aluminum foil.
- Bake for 1 1/2 hours until the potatoes are tender. For a golden top, remove the foil during the final 15 minutes of baking.
- Allow the dish to rest for 10 to 15 minutes before serving so the sauce can thicken into a perfect scoopable texture.
Notes
Pro Tip: Grate your own cheese from a block rather than using pre-shredded bags to ensure a perfectly smooth, glossy sauce without grainy anti-caking agents.
Texture Secret: Use a mandoline to achieve uniform 1/8-inch slices, ensuring every potato layer softens at the same rate for a consistent bite.
Safety Note: When using a mandoline, always use the hand guard or a cut-resistant glove to protect your fingers as the potato becomes smaller.
Resting Time: The 15-minute rest period after baking is essential; it allows the starches to settle and the sauce to thicken into a cohesive, plush texture.
Nutrition information is estimated based on common ingredients and serving sizes and may vary.
Nutrition
Calories: 315kcalCarbohydrates: 34gProtein: 11gFat: 16gSaturated Fat: 10gCholesterol: 44mgSodium: 475mgPotassium: 740mgFiber: 3gSugar: 5gVitamin A: 12IUVitamin C: 15mgCalcium: 25mgIron: 8mg
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