If you're trying to eat a bit healthier - maybe a little bit less meat, a little less starch, a bit more veg, then this is the dish for you.
The most important thing about preparing this meal is cooking the aubergines properly before beginning the layering process. These would traditionally be cooked in oil, possibly even dipped in breadcrumbs, but I have been experimenting for some time with the process and have found that the very best way to cook them is quite simply dry frying on a grill pan. Just be sure that the slices are "floppy" when taken off the pan - never assume that undercooked aubergine will finish off in the oven - they very rarely do and there isn't a lot worse (culinary speaking) than raw aubergine!
Just remember if you're making this for vegetarians, use a cheese with a vegetarian rennet (not Parmigiano Reggiano).
For the aubergine
2 large aubergines, sliced into thin slices about a 5mm/¼in thick
100g/3½oz Parmesan, grated (or alternative vegetarian hard cheese)
125g/4½oz mozzarella, sliced
sea salt and freshly ground black pepper
For the tomato sauce
Grill the aubergine slices. Heat a griddle pan and cook the aubergines for a couple of minutes on both sides until lightly browned. Set aside while you get on with the tomato sauce.
Heat a large frying pan. Fry the garlic with a little oil until soft. Add the tomatoes & oregano. Simmer for about 15 minutes, or until the sauce thickens.
Preheat the oven to 220C/200C Fan/Gas 7.
In a medium-sized roasting tin, spread a little tomato sauce over the bottom of the tin. Add a layer of aubergine slices and spread another layer of tomato sauce on top.
Spread half the mozzarella on the top and sprinkle with Parmesan, salt and pepper. Continue to repeat the layers until all the aubergine is used. Finish with a layer of mozzarella slices topped with a final sprinkle of Parmesan. Bake for 25 minutes.
Serve with salad alongside. This dish reheats well if you have any leftovers.