Leek, Fennel, and Poppy Seed Tart Recipe

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