Twice-Cooked Potato-and-Leek Casserole

Photo: Chris Court
Prep Time:
45 mins
Total Time:
1 hrs 20 mins


  • 2 pounds sweet potatoes (about 5 small), peeled and cut into ½-inch pieces

  • 2 pounds russet potatoes (about 7 small), peeled and cut into ½-inch pieces

  • Coarse salt and freshly ground pepper

  • ¾ cup whole milk, warmed

  • ¾ cup heavy cream, warmed

  • 1 ½ sticks unsalted butter, melted

  • 2 tablespoons all-purpose flour

  • Pinch of cayenne pepper

  • 1 leek, white and light-green parts only, cut into ¼-inch rounds, washed well, and dried (about 2 cups)

  • Safflower oil, for frying


  1. Preheat oven to 425 degrees. Cover sweet potatoes and russet potatoes each with 1 inch water in 2 separate medium saucepans. Bring to a boil, salt generously, and boil until fork-tender, about 8 minutes. Drain and return potatoes to respective pans.

  2. In a bowl, combine milk, cream, and butter. Divide milk mixture between saucepans. Mash potatoes until smooth; season with salt and pepper.

  3. Spread mashed sweet potatoes evenly in the bottom of a shallow 2-quart baking dish. Top with mashed russet potatoes; spread evenly to edges. Bake until golden, about 25 minutes.

  4. Meanwhile, in a bowl, combine flour and cayenne. Add leeks; toss to coat. In a medium saucepan, heat 2 inches oil over medium-high heat until a thermometer registers 350 degrees. Working in batches, add leeks and cook, turning, until crisp and light golden around edges, about 1 minute. With a slotted spoon, transfer to paper towels to drain. Season with salt.

  5. Sprinkle fried leeks over potatoes; serve.

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