Keep the eggplant slices in a line on the paper towel. Season them with some salt and let them rest for about 30 minutes.
Now, heat olive oil in a pan. Fry the seasoned eggplants in it. Cook them until they turn golden brown from both sides.
Boil the potatoes in salted water for about 5 minutes. Wash and rinse them with cold water afterwards.
Now, heat some olive oil in a large skillet. Cook the ground beef in it until it turns brown. Cook sausages along with it. Add the onions and garlic to it. Cook them until they become tender for about 5-7 minutes.
Then, add the crushed tomatoes, tomato paste, bay leaf and wine to the skillet. Stir it to mix it well. Boil this mixture and reduce the heat once started boiling. Simmer it and cook it for about 30 minutes until all the liquid is absorbed. Now, let the sauce cool and add the beaten egg to it.
To make the bechamel sauce, add some butter in a skillet and allow it to melt. Add some flour and whisk it well for about 2 minutes. Add the milk and whisk it properly avoiding the formation of any lumps.
Add the parmesan cheese, salt, and nutmeg to this skillet. Whisk the sauce until it becomes thick. Once it’s done, take it off the heat and let it cool for about 15 minutes. Add the egg yolks to it and whisk them well with it.
Grease a baking dish and make a layer of bread crumbs on the bottom of it. Arrange a layer of potatoes on the bottom. Place the eggplants with some sauce on it. Then, completely fill it with the meat sauce that we prepared. Add eggplants on the top of the meat sauce along with some bechamel sauce.
Meanwhile, preheat the oven to 350oF and let this dish bake for about 1 hour.
Take the dish out of the oven and let it rest for about 15 minutes before you start serving. Let the liquid at the bottom get absorbed.