Cut the mozzarella cheese into small cubes. Place it into a colander and let it drain while continuing with the preparation of the recipe.
Slice eggplants around 1,2 cm (1,4″) thick and place them in layers into a colander inside a bowl; sprinkle with salt each layer and set aside for 30 minutes.
Meanwhile, make the tomato sauce. Finely chop 1 onion and sauté with a teaspoon of extravirgin olive oil until translucent. Add the tomato sauce and a some basil leaves torn with your hands. Season with salt and pepper, stir then let it simmer gently for 15 minutes. Set aside.
Enjuagar las berenjenas, secarlas cuidadosamente con papel y freírlas en aceite por ambos lados sin que se doren demasiado.
Now, rinse the eggplant slices under cold water to remove the salt and pat them dry with a kitchen towel or paper. Fry the slices in olive oil until they soft and start to brown.
Put two tablespoons of tomato sauce on the bottom of a baking dish, then add one layer of fried eggplant.
Sprinkle with parmigiano then add mozzarella cubes. Add more sauce, then repeat the layers of eggplant > parmigiano > mozzarella, until all ingredients are gone.
Heat the oven at 190°C / 375°F . Cover loosely the baking dish with foil and bake for 30 minutes. Remove the foil and keep baking for another 15 minutes until cheese is melted and bubbling on top.
Let the parmigiana set for a few minutes before serving.
If you use fresh mozzarella is important to let is drain it’s liquid for a few minutes. Otherwise it will release it when baking it and you’ll end with a soupy dish, instead the firm, well placed layers of vegetables and cheese.
If eggplants are in season there’s not need to let them draw their bitterness. Just slice and fry.
In some southern versions, the slices of eggplant are dredged in flour or bread crumbs before frying.
You can prepare this dish in advance and store it in the fridge until you are ready to bake it.
For a more richer version of this dish, add between layers some thin slices of mortadella.