Preheat the oven to 190ºC / 375ºF / Gas Mark 5. Put the oil in a large bowl, add the courgettes,
peppers, aubergine, onions and shallots and toss well to coat.
Divide the vegetables between 2 baking trays and roast in the preheated oven for 30-40 minutes
until soft and flecked with brown. Add the button mushrooms after 20 minutes.
Remove the vegetables from .the oven and tip into a large bowl. Add the tomatoes and tomato
puree and mix well. Melt the butter in a saucepan over a low heat. Stir in the flour and cook,
stirring constantly, for 2-3 minutes. Gradually add the milk and cook, continuing to stir
constantly, until the sauce is thick and smooth. Season to taste with salt and pepper and stir in
the Cheddar cheese.
Layer the vegetable mixture and sauce in an oven proof dish with the lasagne, finishing with a
layer of sauce. Sprinkle over the Parmesan cheese and bake in the oven for 30-35 minutes.