This crispy French onion scalloped potato casserole combines tender, creamy potatoes with sweet caramelized onions and a golden, cheesy topping. Inspired by classic French onion soup and comforting scalloped potatoes, this dish is rich, cozy, and perfect for holidays, gatherings, or any meal where you want an impressive side that everyone remembers.
Ingredients:
3 pounds russet potatoes, peeled and thinly sliced
2 cups heavy cream
1 cup whole milk
1 large onion, thinly sliced
2 tablespoons olive oil
2 tablespoons unsalted butter
2 cloves garlic, minced
1 teaspoon salt
1/2 teaspoon black pepper
1 teaspoon dried thyme
1 1/2 cups shredded Gruyère or Swiss cheese
1/2 cup shredded mozzarella cheese
1/2 cup grated Parmesan cheese
Optional topping: 1/2 cup French fried onions or breadcrumbs
Instructions:
Preheat the oven to 375°F (190°C). Lightly grease a 9×13-inch baking dish.
Heat the olive oil and butter in a skillet over medium heat. Add the sliced onion and cook slowly for 15 to 20 minutes, stirring often, until soft, golden, and caramelized. Add the garlic and cook for 30 seconds until fragrant. Remove from heat.
In a bowl, whisk together the heavy cream, whole milk, salt, black pepper, and thyme.
Arrange half of the sliced potatoes evenly in the prepared baking dish. Spoon half of the caramelized onions over the potatoes and sprinkle with a portion of the Gruyère, mozzarella, and Parmesan cheeses.
Repeat with the remaining potatoes, onions, and cheeses. Pour the cream mixture evenly over the casserole, gently pressing down so the liquid seeps between the layers.
Cover the dish tightly with foil and bake for 50 to 60 minutes, until the potatoes are tender.
Remove the foil and continue baking for another 20 to 25 minutes, until the top is golden brown and bubbly. If using French fried onions or breadcrumbs, sprinkle them on during the last 10 minutes of baking.
Remove from the oven and let rest for 10 minutes before serving.
Serving Suggestions:
Serve alongside roasted meats, chicken, or holiday dishes.
Pair with a crisp green salad to balance the richness.
Tips for Best Results:
Slice potatoes evenly for consistent cooking.
Caramelize the onions slowly for the best flavor.
Gruyère adds classic French onion flavor, but Swiss works well too.
Creamy on the inside with a crispy, cheesy top, this French onion scalloped potato casserole is pure comfort and always a show-stopping side dish.