Dad’s Creamy & Cheesy Au Gratin Potatoes Recipe
Dad’s Creamy & Cheesy Au Gratin Potatoes is a comforting baked casserole featuring tender Yukon gold potato slices layered with onions and smothered in a rich, creamy cheddar cheese sauce. Topped with Gruyère, Parmesan, and fresh herbs, this classic side dish boasts a golden, bubbly crust and a melt-in-your-mouth texture perfect for family dinners or special occasions.
- Prep Time: 20 minutes
- Cook Time: 1 hour 15 minutes
- Total Time: 1 hour 35 minutes
- Yield: 6 servings
- Category: Side Dish
- Method: Baking
- Cuisine: American
- Diet: Vegetarian
Ingredients
Potatoes and Onions
- 2 ½ pounds Yukon gold potatoes (6 to 7 medium), 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 Gruyère cheese (½ cup)
- 2 ounces grated Parmesan cheese (½ cup)
- Chopped fresh chives or parsley, for garnish
Instructions
- Preheat and prepare dish: Preheat the oven to 375°F. Lightly spray a 9-inch square baking dish with cooking spray to prevent sticking.
- Arrange potatoes and onions: Layer the sliced Yukon gold potatoes in the baking dish in three or four rows, ensuring they are slightly slanted with space between slices. Distribute the thinly sliced onions between and on top of the potatoes wherever there is space.
- Make the cheese sauce: In a medium pot over medium heat, melt the butter. Whisk in the flour and cook for about 30 seconds until a smooth paste forms. Gradually whisk in the milk, stirring constantly to avoid lumps. Bring the mixture to a boil over medium-high heat, then reduce to medium-low and simmer until thickened, about 5 minutes. Lower heat and stir in the shredded Cheddar cheese, kosher salt, garlic powder, and black pepper. Adjust seasoning to taste.
- Pour sauce and bake covered: Pour the creamy cheddar sauce evenly over the layered potatoes and onions. Cover the baking dish tightly with foil and bake for 45 minutes to allow the potatoes to partially cook and absorb flavors.
- Add toppings and finish baking: Remove the foil and sprinkle shredded Gruyère and grated Parmesan cheeses over the potatoes. Return the dish to the oven, uncovered, and bake an additional 30 to 45 minutes until the potatoes are tender when pierced with a fork and the cheese topping is golden brown and bubbly.
- Optional broil for crispiness: For a crispier, golden crust, switch the oven to broil on high and broil for 1 to 2 minutes, watching carefully to prevent burning.
- Cool and garnish: Let the casserole cool for 10 minutes before sprinkling with chopped fresh chives or parsley. Serve warm for best flavor and texture.
- Storage and reheating: Store leftovers in an airtight container in the refrigerator for up to 5 days. Reheat in the microwave in 30-second intervals until warmed through.
- Make ahead tip: Assemble the casserole as directed but do not bake. Cover with foil and refrigerate for up to 1 day. When ready to serve, bake as instructed, adding 10 to 15 minutes to the bake time if needed.
Notes
- Use Yukon gold potatoes for their creamy texture and optimal cooking performance in au gratin dishes.
- Whole milk creates a richer sauce, but unsweetened almond milk can be substituted for a lighter or dairy-free option.
- Ensure potato slices are thin (⅛ inch) for even cooking throughout the bake.
- Cover with foil while baking initially to steam potatoes gently before crisping the top uncovered.
- Broiling at the end adds a deliciously crispy cheese crust but watch closely to avoid burning.
- This dish can be prepared a day ahead for convenience, making it great for entertaining.
