Preheat the Oven: Set your oven to 200°C (400°F) to ensure it's hot enough for both stages of baking.

Prepare the Eggplants: Wash and slice the eggplants into rounds. Arrange them on a baking tray lined with parchment paper.

Brush both sides of each slice with corn oil and sprinkle with a little salt to help draw out moisture and flavor.

Bake for 20-25 minutes, turning halfway through until they are tender and slightly golden. Remove from the oven and set aside.

Prepare Other Ingredients: While the eggplant is baking, peel and thinly slice the potatoes.

Slice the onion into thin rings.

Layer the Dish: In a baking dish, create layers starting with eggplant slices, followed by potato slices, and onion rings. Repeat the layering process until all the ingredients are used.

Drizzle extra virgin olive oil over each layer, seasoning with salt, black pepper, and oregano to enhance the flavors.

Distribute pieces of Mozzarella cheese and finally, sprinkle the Grana Padano or Parmesan cheese evenly on top.

Bake the Dish: Cover the dish with aluminum foil to prevent excessive browning and to allow the vegetables to cook through without drying out.

Bake covered for 30-35 minutes. Then, remove the foil and continue baking for another 10-15 minutes or until the top cheese layer is melted and golden brown.

Garnish and Serve: Once baked, let the dish sit for a few minutes out of the oven before garnishing with freshly chopped parsley.

Serve warm as a main dish or a side, enjoying the melting cheese and the soft, flavorful layers of vegetables.