French onion scalloped potatoes deserve a spot on your dinner table.
This is another take on the irresistible French onion flavor—this time folded into scalloped potatoes. Caramelized onions seasoned with thyme get mixed into thinly sliced potatoes and layered with lots of melty gruyère for that classic, savory profile.
The combination of sweet, caramelized onions, creamy cheese sauce and tender potatoes is pure comfort.
If you love French onion flavors, this is an easy way to bring them to a side dish. The onions are slowly cooked until deeply caramelized, which adds a rich, savory depth to the potatoes. The result is a luscious, cheesy casserole that’s perfect for holidays or a cozy family meal.
Make it for Easter, a special Sunday dinner, or anytime you want a showstopping side that reheats and travels well.
I know I sure am enjoying it.
Scalloped potatoes can feel a bit involved — slicing the potatoes, making a béchamel-style sauce, grating cheese — and this version asks you to caramelize onions for 40–60 minutes. Real caramelization takes time, but most of it is hands-off. If you slice the potatoes ahead of time, store them in ice water in the fridge so they don’t brown.
If you have a mandoline, it’s handy for uniform, very thin slices, but a sharp knife works fine too.
Gruyère is the ideal cheese here for that French onion soup note. Some gets stirred into the sauce, and more is layered between the potatoes with the caramelized onions. A sprinkling of seasoned breadcrumbs on top gives a crisp finish once baked.
The cheese becomes golden and bubbly, the potatoes melt tender, and the flavors come together beautifully.
They are irresistible.
This recipe is a little labor of love but yields a deeply satisfying, crowd-pleasing side. It’s a great addition to holiday menus, potlucks, or any meal where you want to impress with comfort food.
Below is a clear and polished version of the recipe so you can recreate it at home.
French Onion Scalloped Potatoes
French Onion Scalloped Potatoes
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Ingredients
- 4 sweet onions, thinly sliced
- 4 tablespoons unsalted butter
- kosher salt and pepper
- ½ teaspoon dried thyme
- 3 pounds russet potatoes, peeled
sauce
- 4 tablespoons unsalted butter
- 4 tablespoons all-purpose flour
- 3 ½ cups milk
- kosher salt and pepper
- ¼ teaspoon freshly grated nutmeg
- 12 ounces freshly grated gruyere cheese
- ⅓ cup seasoned bread crumbs
Instructions
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Preheat the oven to 375°F (190°C).
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Thinly slice the onions. Melt 4 tablespoons butter in a large skillet over medium heat. Add the onions and a big pinch of salt and pepper. Cook for about 10 minutes, stirring occasionally, until the onions soften. Reduce heat to medium-low, stir in the thyme, and continue to cook for 30 to 40 minutes, stirring often, until the onions are golden and deeply caramelized. If they begin to burn, lower the heat or add a splash of water; if they aren’t browning, raise the heat slightly.
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Use a mandoline or a very sharp knife to slice the potatoes 1/8 inch thick or thinner. Keep slices uniform. If preparing ahead, store the slices submerged in ice water in the refrigerator to prevent browning.
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Make the sauce: melt the remaining 4 tablespoons butter in a saucepan. Whisk in the flour to form a roux and cook 2–3 minutes until golden and fragrant. Gradually whisk in the milk until the sauce is smooth and combined.
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Season the sauce with salt, pepper and the nutmeg. Reduce heat to low and stir in about 6 ounces (half) of the grated gruyère until melted. Taste and adjust seasoning as needed.
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Assemble: layer half the potato slices in a baking dish. Pour half the cheese sauce over the potatoes, spread half the caramelized onions and sprinkle half the remaining grated gruyère. Repeat with the remaining potatoes, sauce, onions and cheese. Finish with the seasoned breadcrumbs on top.
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Bake uncovered for 45 to 60 minutes, or until the potatoes are very tender and a fork slides through easily. If the top browns too quickly, tent with foil. Let rest for a few minutes before serving.
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Such cheesy goodness.