You will need:
3 or 4 tomatoes. It depends on the size of your tomatoes.
1 onion, sliced
Olive oil for frying the onions.
The first thing that I want to say is that I am not over fond of frying aubergines as I think that they soak up so much oil that the pleasure of eating them in lost in a sea of grease. What I do is slice the aubergines and put them on a microwaveable plate. Cover with cling film and cook until soft. The time that this takes will depend on the power of your microwave. Leave them aside until ready. Do the same with the zucchini.
Fry the onion until soft.
Skin and slice the tomatoes.
Make up the dish by putting layers of alternating vegetables in an oiled, oven proof dish . Cover with a layer of Parmesan cheese and bake in a hot oven for about 30 mins. Most of the vegetables have been pre-cooked so it does not take too long. It should be brown and bubbling like the photograph.
Serve as an accompaniment for grilled meat.