Preheat the oven to 180°C, fan 160°C, gas mark 4.
Heat the olive oil in a pan and add the sliced vegetables. Fry for about 5 minutes, then add the drained cannellini beans and set aside.
Cover the base of a 1.5-litre ovenproof dish with a spoonful of passata, top with a little of the vegetable filling, then cover with one layer of lasagne sheets. Repeat this process until the filling has been used, ensuring you reserve a little of the passata.
Finish with a layer of lasagne sheets and passata, then cover with the sliced mozzarella. Bake for 35 minutes, then serve.