INGREDIENTS

• 3 (about 1 1/2 pounds) Yukon gold potatoes, peeled and cut into 1/4-inch-thick rounds
• Coarse salt
• 1 cup heavy cream
• 5 cloves garlic, crushed with the flat side of a large knife
• 1/2 teaspoon freshly grated nutmeg
• Freshly ground pepper
• 2 tablespoons unsalted butter
• 1 medium leek, white and light-green parts only, halved lengthwise, thinly sliced crosswise, and washed well
• 1/4 cup chopped fresh flat-leaf parsley
• 1 large egg yolk
• 1 (14 ounces) frozen puff pastry, (such as Dufour), thawed
• All-purpose flour, for work surface
• 1 1/2 cups grated Comte or Gruyere cheese

DIRECTIONS

STEP 1
Cover potatoes with water in a medium saucepan. Bring to a boil over high heat. Add a pinch of salt; cook until just tender, 13 to 15 minutes. Drain. Let cool.
STEP 2
Bring 3/4 cup plus 3 tablespoons cream, the garlic, and nutmeg to a boil in a small saucepan over medium-high heat. Cook mixture until reduced by half. Season with salt and pepper; set aside.
STEP 3
Melt butter in a skillet over medium heat. Add leek; cook, stirring occasionally, until softened, about 5 minutes. Remove from heat. Stir in parsley; season with salt and pepper. Set aside.
STEP 4
Preheat oven to 400 degrees. Whisk egg yolk and remaining tablespoon cream in a small bowl; set aside. Divide puff pastry on a lightly floured surface into two 6-by-13-inch rectangles. Set 1 rectangle on a baking sheet lined with parchment paper. Add half of the potatoes, leaving a 1/2-inch border all around and overlapping potatoes slightly. Top with half of the leek mixture and 3/4 cup cheese; season with salt and pepper. Repeat layering with remaining potatoes, leeks, and cheese. Brush edges of dough with egg wash. Cover with remaining dough rectangle; gently press edges with a fork to seal. Cut 2-inch slits lengthwise in center of crust, 2 inches apart. Brush with egg wash. Refrigerate until cold, about 30 minutes.
STEP 5
Bake pie until golden brown and puffy, about 35 minutes. Remove from oven. Pour cream mixture into pie vents with a funnel. Bake 10 minutes more. Let stand 15 minutes before serving.