Preheat the oven to 400°F (200°C).

Slice the eggplant into ½-inch rounds and place them on a baking sheet.

Drizzle the eggplant slices with olive oil and sprinkle with salt and pepper.

Roast the eggplant for about 20 minutes, flipping halfway through.

While the eggplant is roasting, toast the bread slices in a skillet over medium heat until golden brown.

Spread a layer of marinara sauce on each slice of toasted bread, layer with roasted eggplant, and sprinkle with mozzarella cheese.

Place the assembled sandwiches back in the skillet, cover, and cook on low heat until the cheese melts, about 5 minutes.

Remove sandwiches from the skillet, garnish with fresh basil leaves, slice, and serve warm.