Thyme-scented Potato Gratin
By Tested and perfected in the Sur la Table kitchen
Thyme-scented Potato Gratin
By Tested and perfected in the Sur la Table kitchen
Yield/Serves:
Makes 8 to 10 servings
- 3 pounds Yukon Gold potatoes
- 2 large leeks, white and light green parts only, washed well and thinly sliced
- 6 tablespoons fresh thyme leaves, divided
- ½ cup grated Gruyère cheese
- ¼ cup grated Parmesan cheese
- 4 tablespoons unsalted butter, divided, plus more for greasing baking dish
- 1 cup heavy cream
- 1 cup whole milk
- 1 tablespoon kosher salt
- ½ teaspoon freshly ground white pepper
This elegant side dish classic is a crowd pleaser for any occasion. Make sure to wash the leeks thoroughly since they often contain sand in between the layers. But don’t rinse the potato slices, since the starch on their surfaces helps to bind and thicken the gratin. Use a mandoline to cut the potatoes into thin, even slices.
Place 2 tablespoons butter in a large saucepan and heat over medium heat. Add leeks and sauté until softened but not browned, about 4 to 5 minutes.
Add cream and milk to the saucepan and heat until mixture simmers. Add salt and white pepper, stirring well to combine. Peel potatoes and place a mandoline across the top of the saucepan. Slice potatoes into 1/8-inch thick slices directly into hot cream mixture. Press potato slices gently with a silicone spatula to submerge. Cook, undisturbed, until potatoes are partially cooked and mixture begins to thicken, about 10 to 12 minutes. Stir in 3 tablespoons thyme leaves.
Preheat oven to 375°F and place a rack in the center. Generously grease a 13 x 9 x 2-inch baking dish with butter. Combine cheeses in a small mixing bowl. Using a slotted spoon or spider, carefully transfer the potato slices to the prepared baking dish. Carefully pour enough cream mixture to barely cover potatoes. Dot with remaining 2 tablespoons butter and cover with remaining cheese mixture.
Bake in preheated oven until casserole bubbles around the edges, potatoes are tender and the top is golden brown, about 50 to 60 minutes. If the top begins to brown too deeply before potatoes are cooked, cover gratin with aluminum foil. If the top has not browned when potatoes are cooked, place gratin under a preheated broiler for 2 to 3 minutes, continuously watching to ensure it doesn't burn.
Allow gratin to sit for at least 20 minutes before serving.
To serve: Sprinkle gratin with remaining 3 tablespoons thyme leaves. Slice gratin into serving portions and transfer to serving plates. Serve immediately.
Place 2 tablespoons butter in a large saucepan and heat over medium heat. Add leeks and sauté until softened but not browned, about 4 to 5 minutes.
Add cream and milk to the saucepan and heat until mixture simmers. Add salt and white pepper, stirring well to combine. Peel potatoes and place a mandoline across the top of the saucepan. Slice potatoes into 1/8-inch thick slices directly into hot cream mixture. Press potato slices gently with a silicone spatula to submerge. Cook, undisturbed, until potatoes are partially cooked and mixture begins to thicken, about 10 to 12 minutes. Stir in 3 tablespoons thyme leaves.
Preheat oven to 375°F and place a rack in the center. Generously grease a 13 x 9 x 2-inch baking dish with butter. Combine cheeses in a small mixing bowl. Using a slotted spoon or spider, carefully transfer the potato slices to the prepared baking dish. Carefully pour enough cream mixture to barely cover potatoes. Dot with remaining 2 tablespoons butter and cover with remaining cheese mixture.
Bake in preheated oven until casserole bubbles around the edges, potatoes are tender and the top is golden brown, about 50 to 60 minutes. If the top begins to brown too deeply before potatoes are cooked, cover gratin with aluminum foil. If the top has not browned when potatoes are cooked, place gratin under a preheated broiler for 2 to 3 minutes, continuously watching to ensure it doesn't burn.
Allow gratin to sit for at least 20 minutes before serving.
To serve: Sprinkle gratin with remaining 3 tablespoons thyme leaves. Slice gratin into serving portions and transfer to serving plates. Serve immediately.