Start by burning one of the eggplants. This can be done one of several ways. On a gas stove, the eggplant can be put directly on a moderate flame and roasted for 12-15 minutes (turning frequently with metal tongs) until the flesh is soft and smoky and the skin is burnt all over. To roast in the oven, pierce the eggplant with a sharp knife in a few places. Put it on a foil-lined tray and place directly under a hot broiler for 45 minutes, turning a few times. The aubergine needs to deflate completely and its skin should burn and break. It should look very wrinkly. Or you can use the grill and keep turning it, about 20-25 minutes.
Once the eggplant is ready, remove it from the heat and make a long cut through it. Scoop out the soft flesh while avoiding the skin. Discard the skin. Chop the flesh roughly and set aside.
Cut the other eggplant into a 1/2 inch dice, leaving the skin on. Heat up 1/3 cup of the olive oil in a frying pan and fry the eggplant dice in batches until golden and crisp. (you may need more oil).Transfer to a colander and sprinkle with salt. Leave to cool.
Put the onion and remaining oil in a heavy pan and fry slowly until the onion is soft and translucent. Add the garlic and cook for a further 3 minutes. Turn up the heat and add the rice, stirring to coat it in the oil. Fry for 2-3 minutes. Add the wine (it should hiss) and cook for 2-3 minutes, or until nearly evaporated. Turn the heat down to medium.
Now start adding the hot stock to the rice, a ladleful at a time, waiting until each addition has been fully absorbed before adding the next and stirring all the time. When all the stock has been added remove the pan from the heat. Add half of the lemon zest, the lemon juice, grilled aubergine flesh, butter, most of the parmesan and about 3/4 teaspoon salt. Stir well, then cover and set aside untouched for 5 minutes. Taste and add more salt, if you like, plus black pepper.
To serve, spoon the risotto into shallow bowls and sprinkle with the diced eggplant, the remaining parmesan, the basil and the remaining lemon zest.