Cheesy Zucchini & Leek Lasagna

Step 1: Grease a large, rectangular ovenproof dish (10-cup capacity).

Step 2: Heat oil in a large, non-stick frying pan over a medium heat and add leeks and cook, stirring occasionally, for about 5 minutes, or until soft and then add zucchini and garlic and cook, stirring, for about 5 minutes, or until zucchini is tender and then remove from heat.

Step 3: To make sauce, melt butter in a large saucepan over a medium heat until bubbling and then add flour and cook, stirring, for 2 minutes and then remove from heat and gradually whisk in milk and then whisk in mustard and then return to heat and cook, stirring until sauce boils and thickens and then stir in 1½ cups of the cheese and season with salt and pepper.

Step 4: To assemble, arrange one third of the pasta sheets, slightly overlapping, over base of prepared dish and then top with one-third of the zucchini mixture and spread evenly and then pour over 1 1/3 cups of the cheese sauce and repeat layering with pasta sheets, zucchini mixture and sauce.

Step 5: Cover tightly with greased foil and then cook in a hot oven (200°C) for 30 minutes.

Step 6: Remove from oven and discard foil and sprinkle over remaining cheese and return to oven and cook for a further 20 minutes, or until golden brown.

Step 7: Remove from oven and stand for 30 minutes before serving with cracked black pepper.