Description

Dad’s Creamy & Cheesy Au Gratin Potatoes features tender Yukon gold potatoes layered with thinly sliced onions and smothered in a rich, creamy sauce made from three kinds of cheese. This classic, comforting side dish is perfect for holiday dinners or any time you want a luscious, cheesy accompaniment to your meal. The dish is baked until bubbling and topped with a golden, crispy cheese crust, then garnished with fresh chives for a flavorful finish.

Ingredients

Potatoes and Onions

2 ½ pounds Yukon gold potatoes (6 to 7 medium potatoes), sliced into ⅛-inch-thick rounds
½ medium yellow onion, thinly sliced

Sauce

3 tablespoons salted butter
¼ cup all-purpose flour
1 ½ cups whole milk or unsweetened almond milk
8 ounces sharp Cheddar cheese (2 cups), shredded
¾ teaspoon kosher salt, plus more to taste
½ teaspoon garlic powder
Freshly ground black pepper, to taste

Toppings

2 ounces shredded Gruyere cheese (½ cup)
2 ounces grated Parmesan cheese (½ cup)
Chopped fresh chives or parsley, for garnish

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Instructions

Preheat and Prepare Dish: Preheat the oven to 375°F (190°C). Spray a 9-inch square baking dish with cooking spray to prevent sticking.
Arrange Potatoes and Onions: Place the sliced potatoes in the baking dish in three or four rows, spacing them so they are slightly slanted and not tightly packed. Distribute the thinly sliced onions between and on top of the potatoes wherever there is space.
Make the Cheese Sauce: In a medium pot, melt 3 tablespoons of salted butter over medium heat. Whisk in ¼ cup all-purpose flour and cook for about 30 seconds until a paste forms, whisking constantly. Gradually add 1 ½ cups milk while whisking to avoid lumps. Increase heat to medium-high, bring to a boil, then reduce heat to medium-low and simmer, stirring occasionally, until the sauce thickens to creamy gravy consistency, about 5 minutes. Lower the heat and stir in 8 ounces shredded sharp Cheddar cheese, ¾ teaspoon kosher salt, ½ teaspoon garlic powder, and freshly ground black pepper to taste. Adjust seasoning as needed.
Bake Covered: Pour the cheese sauce evenly over the arranged potatoes and onions. Cover the baking dish tightly with foil and bake in the preheated oven for 45 minutes.
Add Toppings and Continue Baking: Remove the foil and sprinkle the shredded Gruyere and grated Parmesan cheeses evenly over the top. Return the dish uncovered to the oven and bake for an additional 30 to 45 minutes, or until the potatoes are tender when pierced with a fork and the top is golden brown.
Optional Broil for Crispiness: For an extra crispy topping, switch the oven to the broiler setting on high and broil the potatoes for 1 to 2 minutes, watching closely to prevent burning.
Rest and Garnish: Let the dish cool for about 10 minutes before serving. Garnish with chopped fresh chives or parsley for a burst of fresh flavor.
Storage: Store leftovers in an airtight container in the refrigerator for up to 5 days. Reheat in the microwave in 30-second intervals until warm.
Make-Ahead Instructions: Assemble the dish as directed but do not bake. Cover with foil and refrigerate for up to 1 day. When ready to serve, bake as directed, adding 10 to 15 minutes of extra baking time if needed.

Notes

Use Yukon gold potatoes for their creamy texture and ability to hold their shape when baked.
You can substitute whole milk with unsweetened almond milk for a dairy-free alternative, though the flavor will be less rich.
Thinly slicing potatoes and onions ensures even cooking and a creamy texture.
Make sure to whisk continuously when making the sauce to prevent lumps.
The broiling step is optional but adds a deliciously crispy, golden cheese crust.
Leftovers reheat well, making this a great dish to prepare ahead of time.
Adjust salt and pepper seasonings according to taste before baking.

Prep Time: 30 minutes
Cook Time: 1 hour 15 minutes
Category: Side Dish
Method: Baking
Cuisine: American