Heat half the olive oil in a large frying pan, fry half the eggplant slices over high heat, turning frequently, until golden and cooked through (4-5 minutes). Drain on absorbent paper. Season to taste with sea salt and freshly ground black pepper. Repeat with remaining olive oil and eggplant slices.
Preheat oven to 200C. Place 4 rounds of eggplant in a small roasting pan, top each with mozzarella, scatter with oregano. Repeat with remaining eggplant slices, mozzarella and oregano, alternating layers and finishing with mozzarella. Pour passata around eggplant and bake until cheese has melted (5-7 minutes).
Meanwhile, for parmesan crumbs, combine breadcrumbs and parmesan on an oven tray, drizzle with olive oil and season to taste. Toast in oven, stirring occasionally, until golden (5 minutes).
Serve eggplant, scattered with parmesan crumbs, with rocket and parmesan salad to the side.