Preheat oven to 425. Spray baking sheet with cooking spray.
Combine onion and mayo, mixing well. Dip both sides of eggplant into the mayo mixture, making sure to completely coat.
Combine bread crumbs and Italian seasoning in dish, mix well. Dip eggplant into the bread crumbs on both sides. Making sure to fully coat each side. Place onto greased baking sheet.
Put into oven and bake 15 minutes. Run eggplant over and bake another 15 minutes.