First wash your aubergines, slice them lengthways and place them on a plate or in a colander sprinkled generously with salt. Let them rest for about 30 minutes.
Prepare your tomato sauce by placing olive oil in a pan, a garlic clove and the chopped onion. Fry gently until the onion is soft and then add the passata, salt and pepper. Cook for about 20 minutes and add the fresh basil at the very end.
After the sauce is ready, set it to rest while you fry the aubergines. First rinse the salt off the aubergines, pat them dry and dust them in flour on both sides. Heat the sunflower oil in a large frying pan over medium high heat. Add the aubergine slices and fry till golden on both sides. Fry just a few at a time, taking care not to overcrowd the pan, and then remove them and drain on kitchen roll.
Spread 2 spoonfuls of tomato sauce on the bottom of a baking dish and then add a layer of aubergines, a layer of passata, a layer of sliced boiled eggs, the mozzarella and finally the grated Parmesan. Continue until the ingredients are finished (at least two layers) making sure that the top layer of aubergines has just passata and Parmesan on top.
Bake in a preheated 200 C / Gas 6 oven for 30 minutes. Let rest 10 minutes before serving.