Tomato sauce
Slice the aubergines lengthways 3-5mm thick. Salt them for an hour or two, then rinse, squeeze dry and blot before you cook (dry not sodden).
In a pan add the tomatoes, onion, garlic and chilli with salt and pepper, and simmer gently for 45 minutes or until good and thick. Blend to a purée, then stir in the olive oil.
Heat 5ml oil in your widest frying pan until smoking hot. Dust the sliced aubergines in flour, and fry, turning once, to colour both sides golden brown. Drain them well.
In a baking dish spread a spoonful of the sauce on the bottom, then a single layer of aubergines. Spread a little more sauce over, then Parmesan, mozzarella and basil. If the sauce and aubergines were well seasoned, you won't need any more salt. Repeat until all is used up, about five or six layers. Top the last layer of aubergine with the last of the sauce and both cheeses but no basil, which would burn.
Bake in a preheated 220°C/Gas 7 oven for about 35-40 minutes. The dish is done when golden brown on top and starting to bubble in the middle. Leave to rest for at least 15 minutes before serving.