Mixing a potato gratin with Hasselback roast potatoes, we tend to deliver the best creamy-in-the-middle, crispy-on-top casserole. It’s excellent for the Thanksgiving or Christmas table, or any night you would like a show-stopping dish.

Ingredients

• 3 oz finely grated Gruyère cheese

• 2 oz finely grated Parmigiano-Reggiano cheese

• 2 cups heavy cream

• 3 garlic cloves, minced

• 1 tablespoon fresh thyme leaves, roughly chopped

• Kosher salt and freshly ground black pepper, to taste

• 3–4 pounds russet potatoes (5–6 medium), peeled and sliced ⅛ inch thick (use a mandoline for even slices)

• 2 tablespoons unsalted butter, for greasing

Instructions

1. Preheat the Oven

Adjust the oven rack to the middle position and preheat to 400°F (200°C).

2. Prepare the Cheese and Cream Mixture

1. In a large bowl, combine the Gruyère and Parmigiano-Reggiano cheeses.

2. Set aside ⅓ of the cheese mixture for topping later.

3. To the remaining cheese, add the heavy cream, minced garlic, thyme, salt, and pepper. Mix well to combine.

3. Coat the Potatoes

1. Add the sliced potatoes to the cream mixture.

2. Toss gently with your hands, making sure each slice is coated and separated so the creamy mixture seeps between every layer.

4. Assemble the Gratin

1. Grease a large oven-safe skillet or baking dish generously with butter.

2. Take a small handful of potato slices, stack them neatly, and arrange them vertically in the dish.

3. Continue working around the perimeter and into the center until all slices are tightly packed.

   • If needed, slice an extra potato, coat it with the cream mixture, and add it to fill any gaps.

4. Pour any remaining cream mixture evenly over the potatoes, stopping when the liquid reaches about halfway up the sides of the dish. (You may not need all of it.)

5. Bake the Gratin

1. Cover the dish tightly with foil and bake for 30 minutes.

2. Remove the foil and continue baking until the top is a pale golden brown, about 30 minutes more.

6. Add Cheese and Finish

1. Remove the dish from the oven. Sprinkle the reserved cheese evenly over the top.

2. Return to the oven and bake until the top is deep golden brown and crisp, about 30 minutes.

7. Rest and Serve

Remove from the oven and let the gratin rest for 5–10 minutes before serving. This helps the layers set for cleaner slices.

Tips & Notes

• Cheese choice: Gruyère adds a nutty richness, while Parmigiano-Reggiano brings sharp, salty depth.

• Uniform slices: Use a mandoline for consistent ⅛-inch slices to ensure even cooking.

• Advance prep: Assemble the gratin up to 6 hours ahead and refrigerate, covered. Bake just before serving.

Make-Ahead & Storage

• Make-Ahead: Assemble and refrigerate, covered, for up to 6 hours.

• Storage: Store leftovers in an airtight container in the fridge for up to 3 days.

• Reheating: Warm in a 350°F oven until heated through for best texture — avoid microwaving, as it softens the crisp top.

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