Creamy Potato and Leek Gratin
A luxurious French-style gratin combining tender sliced potatoes and leeks in a rich cream sauce, flavored with fresh thyme. This comforting dish features layers of thinly sliced russet potatoes and buttery leeks baked until golden and bubbling.
Ingredients
- •9 whole medium leeks
- •3 Tbsp unsalted butter
- •2 lb russet potatoes
- •1½ cups heavy cream
- •1 cup whole milk
- •2 tsp thyme leaves
- •1 piece adjustable-blade slicer
Cooking Instructions
- 1.
Preheat oven to 400°F with rack in middle. Generously butter a 3-qt shallow baking dish. Cut a round of parchment paper to fit just inside a 12-inch heavy skillet, then set parchment aside.
5 min
- 2.
Halve leeks lengthwise, then cut crosswise into 1 1/2-inch pieces (you should have about 8 cups). Wash leeks.
10 min
- 3.
Cook leeks in butter with 1/2 tsp salt and 1/4 tsp pepper, covered with parchment round, in skillet over medium heat, stirring occasionally, until tender, 10 to 12 minutes.
12 min
- 4.
Meanwhile, peel potatoes and slice crosswise 1/16 inch thick with slicer. Transfer to a large heavy pot with cream, milk, thyme, 1 tsp salt, and 1/2 tsp pepper and bring to a boil over medium heat, stirring occasionally (liquid will thicken). Stir in leeks, then transfer to baking dish.
15 min
- 5.
Bake, uncovered, until potatoes are tender, 45 minutes to 1 hour. Let stand 10 minutes before serving.
60 min
- 6.
Gratin can be baked 2 days ahead and chilled. Let stand at room temperature 30 minutes, then reheat, covered, in a 350°F oven until hot, about 30 minutes.
30 min
