Lay one layer of lasagna sheets (4 sheets) in the bottom of the greased roasting pan.
Pour half of the vegetable mixture over the sheets, spreading out evenly.
Pour over one-third of the white sauce and spread it over the vegetables.
Lay another layer of lasagne sheets (4 sheets).
Spread over the remaining half of the vegetables.
Pour and spread over the second-third of the white sauce.
Lay another layer of lasagne sheets (final 4 sheets).
Pour and spread over the remaining one-third of the white sauce.
Sprinkle the remaining (1 cup/100g) grated cheese over the white sauce.
Bake for 40-45 minutes or until the top is golden and crispy.
Remove from the oven and allow it to rest uncovered, for 15-20 minutes before serving, if desired. Resting the lasagna will make it thicker and prevent it from being sloppy when served.
Garnish with fresh basil leaves if desired.
Serve and enjoy!
Store any leftovers still in the roasting/baking pan, tightly wrapped in cling film, including the sides of the pan, then cover it in foil. Refrigerate for 2-3 days. Or store leftovers in individual serving sizes, wrapped in cling film and foil, or in an airtight container, refrigerated, for 2-3 days.