Pre-heat oven to 180°C.
Heat olive oil in large saucepan over medium-low heat.
Add onion, leek, celery, zucchini, capsicum and cauliflower and cook with lid on for 10 minutes, stirring occasionally.
Add sweet potato and cook uncovered for 5 minutes.
Add canned tomatoes and simmer over low heat for 25-30 minutes, stirring occasionally.
Add a little water if the mixture is too thick.
Melt the margarine in a saucepan over medium heat.
Add the flour. Cook, stirring with a wooden spoon, for 1 minute or until bubbling. Remove from heat.
Gradually add milk, stirring to prevent lumps forming. Return pan to heat. Cook, stirring, for 5 minutes or until sauce boils and thickens.
Remove pan from heat. Stir in half the cheese, stirring until melted and mixed through. Set aside. Assemble straight away to prevent the béchamel sauce from solidifying.
To make 10 portions of the lasagne, lightly spray an 8cm deep, 26 x 36cm baking dish. Place 1/3 of the lasagne sheets on the base of the baking dish, spoon ½ the vegetable mixture onto the sheets and cover with 1/3 of the béchamel sauce.
Repeat with 2 more layers. Spoon béchamel sauce over top. Sprinkle with remaining cheese. Bake at 180°C for 40 minutes or until the top is golden. Stand for 10 minutes. Cut into portions of 250g or portion the pan into 10 portions and serve.
Serving Size 250g