Peel the eggplant and slice into approximately 1/4-inch thick rounds.

Prepare a batter by whisking together the egg, flour, and milk in a bowl until smooth.

Dip each eggplant slice into the batter, ensuring it is fully coated.

Heat olive oil in a large skillet over medium-high heat.

Fry the battered eggplant slices in the hot oil until golden brown on both sides.

Remove the fried eggplant slices and place them on a paper towel-lined plate to drain excess oil.

Preheat oven to 375°F (190°C).

In a baking dish, spread a thin layer of tomato sauce.

Arrange a layer of fried eggplant slices over the sauce.

Sprinkle with Parmesan cheese and mozzarella cheese.

Repeat layers of sauce, eggplant, and cheeses until all ingredients are used, finishing with a layer of cheese on top.

Bake in the preheated oven for 20-25 minutes, or until the cheese is melted and bubbly.

Let cool slightly before serving.