Wash the tomatoes, cut them into large pieces, and place them in a pot with the onion, olive oil, salt, and basil leaves. Cook everything together without sautéing for about 20 minutes. Then puree the mixture using a food mill or blender.

While the sauce cooks, peel the eggplants and slice them into pieces that aren't too thin. For the batter, combine the eggs and flour with a splash of milk in a large bowl. Whisk until smooth and free of lumps, making a batter that's not too thick (the flour amount is usually adjusted by eye).

Tip: Eggplant parmigiana is best enjoyed warm or at room temperature.