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A close-up of a baked Creamy Potato Leek Gratin in a dish with a portion removed, showing the creamy interior and golden-brown cheesy top.

Creamy Potato Leek Gratin

This recipe provides instructions for making a rich potato leek gratin. It combines tender leeks and thinly sliced potatoes baked in a creamy, cheesy sauce.
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Prep Time 20 minutes
Cook Time 1 hour
Cooling Time 5 minutes
Total Time 1 hour 25 minutes
Servings: 6 servings
Course: Side Dish
Cuisine: French
Ingredients Equipment Method Notes

Ingredients
  

For the Gratin
  • 2 tablespoons unsalted butter more for greasing the pan
  • 2 large leeks trimmed and halved lengthwise
  • 1.5 pounds Yukon Gold potatoes peeled
  • 1 teaspoon kosher salt
  • 0.5 teaspoon ground black pepper
  • 2 thyme sprigs
  • 1 cup heavy cream
  • 1 fat garlic clove finely chopped
  • 1 bay leaf
  • 0.25 teaspoon freshly ground nutmeg
  • 0.75 cup Gruyère grated

Equipment

  • 2-quart gratin dish
  • Mandoline or sharp knife
  • Large skillet

Method
 

  1. Heat the oven to 350 degrees and butter a 2-quart gratin dish. Wash the leeks to remove grit and slice them thinly crosswise.
  2. Use a mandoline or sharp knife to slice the potatoes into rounds, ⅛-inch thick. Toss the potato rounds with ¾ teaspoon salt and ¼ teaspoon pepper. Layer the rounds in the prepared gratin dish.
  3. Melt the 2 tablespoons of butter in a large skillet over medium heat. Add the leeks, remaining salt and pepper, and thyme. Cook, stirring, until the leeks are tender and golden, which takes 5 to 7 minutes. Discard the thyme sprigs and scatter the cooked leeks over the potatoes.
  4. Add the cream, garlic, and bay leaf to the skillet. Scrape up any browned bits from the bottom of the pan. Simmer gently for 5 minutes. Stir in the nutmeg.
  5. Pour the cream mixture over the leeks and potatoes. Top the dish with the grated Gruyère. Cover the dish with aluminum foil and place it in the oven. Bake for 40 minutes. Uncover the dish and continue baking until the cheese is bubbling and golden, about 15 to 20 minutes longer. Let the gratin cool slightly before you serve it.

Notes

This dish is a satisfying side for a meal. If you are following a low-carb diet, you might consider substituting the potatoes with cauliflower to maintain a similar texture and flavor profile.

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