Slice the eggplant into ½ inch (1cm) thick rounds. Dip each slice first into the beaten eggs, allowing any excess to drip off, then coat in the flour, shaking off any extra so you have just a light, even coating.

Heat 1 tablespoon of olive oil in a large frying pan over medium-high heat. Working in batches, add the eggplant slices and cook for 3–4 minutes on each side until they turn golden brown and tender. Add more oil between batches as needed to prevent sticking. Use a slotted spoon to transfer the cooked eggplant to paper towels to drain excess oil. While the eggplant cools, preheat your oven to 375°F (190°C).

Heat another tablespoon of olive oil in a saucepan over medium heat. Add the onions and cook gently, stirring occasionally, until they soften and become translucent. Stir in the tomatoes, tomato paste, garlic, and basil. Bring the sauce to a boil, then reduce the heat and let it simmer for 10–15 minutes until it thickens and the flavors concentrate. Add the sugar to balance the acidity and season with salt and pepper to taste.

Begin assembling the dish by spreading some of the tomato sauce across the bottom of a shallow ovenproof dish. Layer the fried eggplant slices over the sauce, then add a layer of mozzarella cheese followed by a sprinkling of Parmesan. Repeat these layers—sauce, eggplant, mozzarella, Parmesan—until all ingredients are used, finishing with a final layer of tomato sauce topped generously with both cheeses.

Place the dish in the preheated oven and bake for 15–20 minutes until the cheese on top is melted, bubbling, and lightly browned. Remove from the oven, let it rest for a few minutes, then serve hot.