American
Gruyère-Crusted Potato Gratin
Thin Yukon Gold slices bake in garlic-thyme cream until silky and cohesive, then emerge beneath a deeply browned Gruyère crust with clean layers that hold after resting.
8 servings · 25 minutes prep · 80 minutes cook
Ingredients
Potatoes and Cream
- 2 tablespoons unsalted butter, divided
- 2 garlic cloves, finely grated
- 2 cups heavy cream
- 1 cup whole milk
- 3/4 teaspoon dried thyme
- 1/8 teaspoon freshly grated nutmeg
- 2 teaspoons Diamond Crystal kosher salt
- 1/2 teaspoon freshly ground black pepper
- 3 pounds Yukon Gold potatoes, peeled and sliced 1/8 inch thick with the mandoline guard or a cut-resistant glove; finish end pieces with a chef's knife
Gruyère Crust
- 8 ounces Gruyère, coarsely grated
- 1 ounce finely grated Parmigiano-Reggiano
Directions
Season and Start the Potatoes
- Heat the oven to 375°F (190°C). Rub a 9-by-13-inch shallow baking dish with half the butter. Melt the remainder in a large saucepan over medium-low, add the garlic, and cook for 30 seconds without browning.
- Add the cream, milk, thyme, nutmeg, salt, and pepper. Bring just to a simmer.
- Slide in the potatoes and simmer gently for 5 to 7 minutes, turning with a wooden spoon, until slices bend slightly and the cream lightly coats them. Stop before the potatoes become tender or break.
Layer and Bake Covered
- Lift and arrange the potatoes in overlapping layers in the prepared dish, distributing the seasoned cream between layers. Press gently so the top is level and most slices sit just beneath the cream.
- Cover tightly with foil and bake for 40 minutes. Insert a thin knife into the center; it should pass through with slight resistance. If the center still crunches, cover and bake for 10 minutes more.
Brown the Cheese Crust
- Remove the foil and combine the Gruyère with the Parmigiano-Reggiano. Scatter evenly to the edges without pressing.
- Bake uncovered for 20 to 25 minutes, until the cream bubbles thickly around the perimeter and the cheese is mottled deep gold. If the potatoes are tender but the top is pale, broil for no more than 1 to 2 minutes, watching constantly.
- Rest on a rack for 20 minutes before cutting. A clean center slice should stand in visible layers with no pool of thin cream on the plate.
