Description

This Sheet Pan Scalloped Potatoes recipe features thinly sliced Yukon Gold potatoes layered with sautéed onions, creamy Dijon-infused heavy cream, and a generous combination of Gruyere and Parmesan cheeses. Baked to golden perfection on a rimmed baking sheet, this dish offers a delightful balance of creamy, cheesy, and crispy textures, perfect as a comforting side for any meal.

Ingredients

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Vegetables & Aromatics

1 medium yellow onion, peeled and diced
3 pounds medium Yukon Gold potatoes, cut into 1/8-inch slices
2 tablespoons chopped fresh rosemary or thyme leaves (optional)

Fats & Oils

1 tablespoon unsalted butter
2 tablespoons olive oil

Dairy & Cheese

12 ounces grated Gruyere (Emmental, Jarlsburg, or Swiss cheese)
1 cup grated Parmesan cheese
2 cups heavy cream

Seasonings & Condiments

1 tablespoon Dijon mustard
Freshly grated black pepper (to taste)

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Instructions

Prepare Oven and Baking Sheet: Line a large, rimmed baking sheet with nonstick cooking spray and preheat the oven to 450°F (232°C).
Sauté Onions: Heat a large skillet over medium-low heat, add olive oil and butter. Once butter melts and oil is hot, add diced onions and cook, stirring frequently, until softened and translucent, about 5 minutes.
Slice Potatoes: While onions cook, scrub and dry the potatoes, then thinly slice them into 1/8-inch rounds. Pat the slices dry with paper towels to remove excess moisture.
Arrange Potatoes: Layer the potato slices in a shingled pattern on the prepared baking sheet. Arrange so the rows barely touch and the potatoes fill the pan evenly.
Season and Add Cheese: Season the potatoes with freshly grated black pepper. Sprinkle half of the Gruyere cheese followed by half of the Parmesan cheese evenly over the potatoes.
Prepare Cream Mixture: Increase heat to medium in the skillet with onions and add heavy cream, Dijon mustard, and chopped herbs if using. Stir continuously and warm the mixture just to a simmer.
Pour Cream Mixture: Carefully pour the hot cream and onion mixture over the layered potatoes, tilting the pan in all directions to distribute the liquid thoroughly. Add more freshly ground black pepper on top.
Top with Remaining Cheese: Sprinkle the remaining Gruyere over the potatoes, then top with the rest of the Parmesan cheese.
Cover with Foil: Spray a sheet of aluminum foil with nonstick cooking spray on one side and cover the potatoes with the sprayed side facing down to prevent sticking.
Bake Covered: Bake the covered potatoes at 450°F for 15 minutes.
Bake Uncovered: Remove the foil, reduce the oven temperature to 375°F (190°C), and bake uncovered for an additional 40–45 minutes until the potatoes are tender in the center, edges are crispy, cheese is bubbly, and the top is golden brown.
Rest Before Serving: Remove from the oven and let the scalloped potatoes rest for 15 minutes to set before slicing and serving.
Enjoy: Serve warm as a delicious side dish alongside your favorite main courses.

Notes

For best results, slice potatoes uniformly thin (1/8 inch) to ensure even cooking.
Patting potatoes dry removes excess starch and moisture, preventing sogginess during baking.
Freshly grated black pepper enhances the flavor dramatically—as opposed to pre-ground.
Using a mix of Gruyere and Parmesan provides a rich, nutty flavor and beautiful gratin crust.
Spraying the foil prevents cheese from sticking and makes removal easier.
Allowing the dish to rest before serving helps it set and improves slicing.
Optional herbs like rosemary or thyme add aromatic notes but can be omitted if preferred.