• On a cutting board, remove the ends of the leeks. Cut them lengthwise on the side and discard the outer, tougher leaf. Then cut them into cylinders about 10 cm (4 inches) long.
• Next, flake them, being careful not to break them. Peel off the most intact and even layers. Each leek will make several cylinders. Select the largest ones.
• Boil the leek cylinders in lightly salted water for a few minutes. Drain and set aside.

Prepare the Filling

• In a bowl, place 250 g (1 cup) of ricotta, 100 g (~ 1 cup) of grated Parmigiano Reggiano and 2 eggs. Mix well.
• Then add a pinch of salt, a little nutmeg and the zest of ½ organic lemon. Mix well and set aside.

Make the Béchamel Sauce

• In a pan, prepare the "roux" by melting 50 g (1.7 ounce or ¼ cup) of unsalted butter and adding 50 g (1.7 ounce or 4 tablespoons) of all-purpose flour. Stir with a hand whisk to remove any lumps.
• Pour the 500 ml (2 cups) of warm milk into the roux, stirring quickly with a hand whisk. Season with ¼ teaspoon of fine salt and a little nutmeg. Cook over medium heat, stirring constantly, until the béchamel has reached the desired consistency.

Assemble the Leek Cannelloni

• Stuff each leek leaf with a tablespoon of filling and roll up.
• Cover the bottom of a baking dish with two tablespoons of béchamel sauce and arrange the leek cannelloni with the opening facing down.
• Then cover all the cannelloni with a layer of béchamel sauce.
• Now make a second layer of stuffed leeks. Finish with more béchamel sauce and grated Parmigiano cheese.
• Bake at 180°C (356°F) for about 20 minutes or until the top is well browned. Remove from oven and let stand for a few minutes before serving.