These Cheesy French Onion Scalloped Potatoes are rich, creamy, and loaded with caramelized onions and melty cheese. If you love a good (and possibly the best!) scalloped potato, you’ll definitely want to check out my popular Cheesy Scalloped Potatoes recipe too; it’s another favorite that’s always a crowd-pleaser. Curious about scalloped vs. au gratin potatoes? Check out my quick guide!
Ingredients & Substitutions
- Unsalted butter: Use for both caramelizing the onions and making the cheese sauce. You can substitute salted butter and adjust the added salt as needed.
- Yellow onions: Thinly sliced for caramelization. White or sweet onions can also be used.
- Russet potatoes: Peeled and sliced for even baking. Yukon Gold potatoes are a slightly creamier alternative.
- All-purpose flour: Forms the roux for the cheese sauce. Gluten-free flour blends work as a substitute if needed.
- Milk: Whole milk adds richness; 2% milk or plant-based milk can be used for a lighter version.
- Cheddar cheese: Mild cheddar melts smoothly; sharp cheddar adds more tang.
- Gruyère cheese: Adds a nutty, creamy layer. Swiss cheese can substitute if needed.
FAQs
Can I Make Cheesy French Onion Scalloped Potatoes Ahead of Time?
Yes! Assemble the casserole, cover tightly with foil, and refrigerate up to 1 day ahead. Bake as directed, adding 5-10 extra minutes if starting from cold.
How to Get Perfectly Caramelized Onions
Caramelizing onions takes patience, but a few tips make them turn out beautifully every time. Cook low and slow, stirring frequently, until onions are deeply golden. For more guidance, check out my Caramelized Onions post, which covers timing, techniques, and tips for perfectly sweet, golden onions.
Can I Use a Different Cheese?
Absolutely! Swiss, Havarti, or fontina can replace Gruyère. Cheddar can be swapped for Colby or Monterey Jack if desired.
Can I Make This Recipe Lighter?
Yes! Use 2% milk instead of whole milk and swap part of the butter in the cheese sauce for a little olive oil. Reducing Gruyère slightly will still keep it creamy while lightening it up.
Can I Use a Different Potato?
Russets are best for their starchy texture, but Yukon Gold or even red potatoes work, too. Cooking time may vary slightly depending on the variety.
Serving Ideas
- Pair with roasted meats, baked chicken, or holiday turkey like my Spatchcock turkey or Cowboy Butter Turkey.
- Serve alongside a fresh side salad or wedge salad for a balanced meal.
- Sprinkle with extra cheese or fresh herbs for a festive presentation.
How to Store Cheesy French Onion Scalloped Potatoes
Room Temperature: Do not leave out for more than 2 hours.
Refrigerator: Store leftovers in an airtight container for up to 3 days. Reheat in the oven at 350°F until warmed through.
Freezer: This casserole can be frozen for up to 2 months. Thaw overnight in the refrigerator and reheat in the oven until hot.
Perfect as a side for holiday dinners like your Thanksgiving and Christmas menus, family suppers, or any time you want indulgent comfort food without complicated steps.
Cheesy French Onion Scalloped Potatoes
Ingredients
- 4 tablespoons unsalted butter, divided
- 2 large yellow onions, thinly sliced into rings
- 4 Russet potatoes, about 2 pounds, peeled and sliced into ¼-inch thick rounds
- 2 tablespoons all-purpose flour
- ½ teaspoon kosher salt
- 1 ½ cups whole milk, room temperature
- ¾ cup (85 g) mild cheddar cheese, shredded, divided
- ¾ cup (85 g) Gruyère cheese, shredded, divided
- salt, to taste
- parsley, chopped for garnish
Instructions
- In a large skillet over medium-low heat, melt 2 tablespoons butter. Add sliced onions and cook, stirring frequently, until they are deeply golden and caramelized, about 30-45 minutes. Set aside.
- Preheat the oven to 400°F. Lightly spray an 8×8-inch casserole dish with nonstick cooking spray. Set aside.
- In a medium saucepan over medium heat, melt the remaining 2 tablespoons butter. Whisk in flour and kosher salt, and cook, whisking constantly, for 1 minute to form a roux.
- Slowly whisk in the milk, making sure there are no lumps. Continue to cook, whisking frequently, until the sauce thickens and begins to bubble, about 5-7 minutes.
- Remove from heat and stir in ½ cup shredded cheddar and ½ cup Gruyère, reserving the remaining ¼ cup of each for topping. Stir until smooth.
- Arrange all of the potato slices in an even, overlapping layer in the prepared casserole dish. Pour the cheese sauce evenly over the potatoes, gently tilting the dish or using a spatula to help it seep between layers.
- Spread the caramelized onions evenly over the cheesy potatoes. Then, sprinkle the remaining ¼ cup of cheddar and ¼ cup Gruyère on top.
- Cover the dish tightly with aluminum foil and bake for 85-90 minutes, or until the potatoes are tender when pierced with a fork. Remove the foil for the last 10 minutes of baking to allow the top to brown. For an extra golden, crisp top, broil for 2-4 minutes, watching closely to prevent burning.
- Let cool for 5-10 minutes before serving. Salt to taste and garnish with parsley.
Did you make this recipe?
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What the Test Kitchen had to say about this recipe:
Autumn
Wow! I love the caramelized onions with these potatoes. They really elevate this side dish! I added a little salt to mine, and they were perfect.
Elizabeth
These are fantastic. The mixture of the cheeses is SO good, and the caramelized onions really set these apart from other cheesy potatoes.
Stephanie
I want to make these this holiday season! What a delicious way to serve potatoes!
Bella
These turned out amazing! The combination of cheddar and Gruyère is so flavorful, and the potatoes cooked up nice and tender.
Super yummy