Description
This French Onion Scalloped Potatoes recipe features thinly sliced russet potatoes layered with rich caramelized sweet onions, creamy gruyere cheese sauce, and a crispy breadcrumb topping. Slow-cooked onions create a deep, sweet flavor that perfectly complements the velvety cheese sauce and tender potatoes, making it an elegant and comforting side dish perfect for family dinners or special occasions.
Ingredients
Scale
Caramelized Onions
- 4 sweet onions, thinly sliced
- 4 tablespoons unsalted butter
- Kosher salt and pepper, to taste
- ½ teaspoon dried thyme
Potatoes
- 3 pounds russet potatoes, peeled and thinly sliced (⅛ inch or thinner)
Cheese Sauce
- 4 tablespoons unsalted butter
- 4 tablespoons all-purpose flour
- 3 ½ cups milk
- Kosher salt and pepper, to taste
- ¼ teaspoon freshly grated nutmeg
- 12 ounces freshly grated gruyere cheese (divided into 6 oz for sauce and 6 oz for layering)
Topping
- ⅓ cup seasoned bread crumbs
Instructions
- Preheat Oven: Preheat your oven to 375°F (190°C) to ensure it is ready when the dish is assembled.
- Caramelize the Onions: Thinly slice the onions. Melt 4 tablespoons of butter in a skillet over medium heat. Add the sliced onions with a generous pinch of salt and pepper. Stir and cook for about 10 minutes until they start softening. Reduce heat to medium-low, stir in dried thyme, and cook the onions for another 30 to 40 minutes, stirring often until they become golden and caramelized. Adjust heat or add water if onions start to burn or aren’t softening.
- Slice the Potatoes: Using a mandoline or a very sharp knife, slice the peeled russet potatoes very thinly (⅛ inch or thinner) ensuring uniform thickness. If preparing in advance, soak the slices in ice water to prevent browning.
- Make the Cheese Sauce: In a saucepan, melt the remaining 4 tablespoons of butter. Whisk in 4 tablespoons of all-purpose flour to create a roux. Cook for 2 to 3 minutes, stirring continuously until the roux is golden and fragrant. Slowly pour in the 3 ½ cups of milk, whisking constantly to avoid lumps and form a smooth sauce. Add salt, pepper, and freshly grated nutmeg. Reduce heat to low and stir in 6 ounces of grated gruyere until melted. Adjust seasoning as needed.
- Assemble the Dish: In a baking dish, layer half of the sliced potatoes evenly. Spread half of the cheese sauce over the potatoes. Next, add half of the caramelized onions and sprinkle half of the remaining 6 ounces of grated gruyere cheese. Repeat this layering process with the remaining potatoes, cheese sauce, onions, and cheese. Finally, sprinkle the top with ⅓ cup of seasoned bread crumbs for a crispy finish.
- Bake: Place the assembled dish uncovered in the preheated oven. Bake for 45 to 60 minutes or until the potatoes are tender when pierced with a fork. If the top browns too quickly, tent with aluminum foil to prevent burning.
- Cool and Serve: Allow the scalloped potatoes to cool slightly before serving to let the sauce set and the flavors meld for optimal taste and texture.
Notes
- Use a mandoline for consistent thin slices of potatoes ensuring even cooking.
- If you notice the onions starting to burn during caramelization, reduce heat or add a splash of water to prevent sticking and scorching.
- The dish can be prepared ahead of time and refrigerated before baking; just add a few extra minutes to the baking time if baking from cold.
- Gruyere cheese adds a nutty, creamy flavor, but you can substitute with Swiss or Emmental cheese if preferred.
- Seasoned bread crumbs add a nice textured topping; plain breadcrumbs can be used and seasoned with a bit of salt and herbs if desired.
Nutrition
- Serving Size: 1 cup
- Calories: 320
- Sugar: 6g
- Sodium: 320mg
- Fat: 18g
- Saturated Fat: 11g
- Unsaturated Fat: 6g
- Trans Fat: 0.2g
- Carbohydrates: 28g
- Fiber: 3g
- Protein: 10g
- Cholesterol: 50mg
