You will need an oven-proof lasagne or a 25-15cm rectangular dish.
3 large firm aubergines
olive oil
1 onion, peeled and finely chopped
3 cloves of garlic, peeled and finely sliced
1 heaped teaspoon dried oregano
2 x 400g tins plum tomatoes (or 1kg fresh ripe tomatoes)
2 x 125g balls of buffalo mozzarella
sea salt and freshly ground black pepper
handful of fresh basil
85g freshly grated Parmesan cheese (or vegetarian alternative)