Ingredients

• 3 1/2 cups thinly sliced leeks (white and pale green parts only; about 3 leeks)
• 1 large fennel bulb, trimmed, cut into 8 wedges, then cut crosswise into 1/4-inch-thick slices
• 4 tablespoons (1/2 stick) butter, melted
• 1 cup whole milk
• 2 large egg yolks
• 1 tablespoon all purpose flour
• 1/2 cup grated Parmesan cheese
• 1 sheet frozen puff pastry (half of 17 1/4-ounce package), thawed
• 2 teaspoons poppy seeds

Instructions

1. Preheat oven to 450°F. Toss leeks, fennel and 3 tablespoons butter in roasting pan. Roast vegetables until tender, stirring occasionally, about 35 minutes. Cool. Reduce oven temperature to 425°F.
2. Whisk milk and yolks in small bowl. Heat 1 tablespoon butter in large saucepan over medium heat. Add flour; whisk 1 minute. Gradually whisk in milk mixture. Bring to simmer, whisking constantly; continue to whisk until sauce thickens slightly, about 3 minutes. Remove from heat. Stir in 1/4 cup cheese. Mix in vegetables. Season with salt and pepper.
3. Roll out pastry on floured surface to 12-inch square. Transfer pastry to 9-inch-diameter glass pie dish. Trim overhang. Fill pastry with vegetable mixture. Sprinkle with 1/4 cup cheese and poppy seeds. Bake until crust is deep golden, about 25 minutes. Serve warm.