A rich and deeply savory potato gratin layered with caramelized onions and two kinds of cheese. A side dish that easily steals the spotlight.

Scale

2 tablespoons olive oil, divided

4 cups thinly sliced onions (about 2 large onions)

6 medium-small Yukon gold potatoes, peeled and thinly sliced (1/8-inch thick, use a mandoline if possible)

3/4 cup (70 g) grated provolone cheese, divided (1/2 cup for tossing, 1/4 cup for topping)

1/2 cup (45 g) grated parmesan cheese

1 teaspoon salt

1/2 teaspoon white pepper (or black pepper)

1 teaspoon butter, diced into small bits

1/4 teaspoon grated nutmeg

1/3 cup (80 ml) vegetable stock (or chicken or beef stock for a non-vegetarian version)

1/2 teaspoon finely minced fresh rosemary

1/2 teaspoon finely minced fresh thyme

1 green onion, chopped (for garnish)

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Step 1: Caramelize the Onions

In a large sauté pan, heat 1 tablespoon olive oil over medium-high heat.
Add onions and stir to coat in oil.
Lower the heat to medium and cook for 15–20 minutes, stirring occasionally, until golden brown and caramelized. Set aside.

Step 2: Preheat and Prep

Preheat the oven to 400°F (200°C).
Butter a large gratin dish or 9×13-inch casserole dish. You can also use individual ramekins.
Spread the caramelized onions in an even layer at the bottom of the dish.

Step 3: Season the Potatoes

In a large mixing bowl, combine sliced potatoes, remaining 1 tablespoon olive oil, ½ cup grated provolone, ½ cup parmesan, salt, pepper, and nutmeg. Toss gently to coat.

Step 4: Assemble the Gratin

Step 5: Bake and Broil

Cover with foil and bake for 45–50 minutes (or 25–30 minutes if using ramekins), until potatoes are fork-tender.
Remove foil and broil uncovered for 5 minutes, or until the top is lightly browned and bubbling.

Step 6: Garnish and Serve

Use a mandoline for uniform potato slices—they’ll cook more evenly.

The caramelized onions can be made a day ahead and refrigerated.

Substitute vegetable stock with mushroom stock for a deeper vegetarian flavor.

Add a layer of thinly sliced tomatoes between the potatoes for added acidity.