Preheat the oven to 200°C conventional oven/ 180°C fan-forced (400° Fahrenheit/Gas 6).
To make the Italian tomato sauce, place the olive oil in a heavy-based stockpot over medium heat. Add the onion and cook until soft. Add the Italian passata and water. Bring to the boil, then add the basil, a pinch of salt and the sugar. Reduce the heat to low and simmer for approximately 45 minutes or until the sauce has reduced to your required consistency, stirring occasionally so that the sauce does not stick to the pot and burn, then remove from the heat. Add additional water, where required.
Slice the eggplant (aubergine) 5-10mm thick – see note. Heat the oil in a large frying pan over medium heat. Fry the eggplant slices, in batches until golden brown (approximately 2 to 3 minutes on each side). Season the eggplant with salt as you cook them and transfer to a plate lined with paper towel. Add more oil if required, and repeat with the remaining eggplant.
Cover the base of a baking dish with a thin layer of Italian tomato sauce. Make a slightly overlapping layer of eggplant slices over the tomato sauce. Spoon 4 tablespoons of Italian tomato sauce over the eggplant, then scatter a layer of basil leaves. Add half of the mozzarella. Repeat the layering with the remaining ingredients, starting and ending with the tomato sauce. Top with a sprinkling of Parmigiano Reggiano and a few basil leaves.
Drizzle with extra virgin olive oil and bake for 30 minutes. Allow to cool for 20 minutes before serving – buon appetito.
Note: In Italy, there are excellent varieties of melanzane (eggplant/aubergine) that are rounded and a vibrant purple colour such as ‘Rosa Bianca’, ‘Violetta di Firenze’, ‘Bianca Sfumata di Rosa’, and ‘Prosperosa’. These varieties have a more delicate flavour and are not bitter. In Australia, I choose Graffiti eggplant (also known as Sicilian eggplant) – they are less seedy and also not bitter. The Italian varieties above and Graffiti eggplant do not need to be salted and rinsed before cooking.
If you are using a black-skinned eggplant, however, you will need to salt the eggplant. To do this, slice the eggplant as per step 3, sprinkle both sides of the eggplant slices with salt and layer in a colander. Set aside for 20 minutes to maximum of 1 hour. Rinse under cold water, drain and use paper towel to pat dry.