Heat oven to 200C/fan 180C/gas 6.
Deseed the peppers, halve, then cut into
large chunks. Trim ends off aubergines,
then cut into slices about ½cm thick.
Lightly grease 2 large baking trays, then
place peppers and aubergines on top.
Toss with the olive oil, season well, then
roast for 25 mins until lightly browned.
Reduce oven to 180C/fan 160C/gas 4.
Lightly oil an ovenproof serving dish
(30 x 20cm). Arrange a layer of the
vegetables on the bottom, then pour
over a third of the tomato sauce. Top
with a layer of lasagne, then drizzle over
a quarter of the white sauce. Repeat until
you have 3 layers of pasta.
To finish, spoon remaining white sauce
over the pasta, making sure the whole
surface is covered. Scatter mozzarella
over the top with the tomatoes. Bake
for 45 mins until bubbling and golden.