Preheat the oven to 375°F (190°C) and line a baking sheet with parchment paper.

Set up a breading station with three shallow dishes: one with flour, one with beaten eggs, and one with a mixture of breadcrumbs and grated Parmesan cheese.

Dip each eggplant slice into the flour, then the egg, and finally coat with the breadcrumb mixture, pressing lightly to adhere.

Heat olive oil in a skillet over medium heat and fry the breaded eggplant slices until golden brown, about 2-3 minutes per side. Transfer to the prepared baking sheet.

Once all slices are fried, place the baking sheet in the oven and bake for 15 minutes to finish cooking the eggplant.

Slice the hoagie rolls and toast them lightly if desired.

Assemble the sandwiches by spreading a layer of warm marinara sauce onto the bottom half of each roll.

Place 2-3 slices of cooked eggplant on top of the marinara sauce, sprinkle with shredded mozzarella cheese, and top with additional marinara sauce if desired.

Close the sandwich with the top half of the roll and, if needed, warm the entire sandwich in the oven for 5 minutes to melt the cheese.

Garnish with fresh basil leaves and serve immediately.