1. Preheat the oven to 180 °C (350 °F). Peel the onion and garlic, roughly chop them, then put them in the food processor fitted with the ultrablade chopping knife. Chop at speed 11 for 30 seconds.
2. Replace the knife with the mixer attachment, add the oil, and start the simmer program P1 at 130 °C (270 °F) for 5 minutes.
3. Then add the tomato pulp and paste, oregano, salt, and pepper, and mix with a spatula. Cut the eggplants into thin slices lengthwise. Fry them for a few minutes in a pan, then place them on paper towels. Grease a gratin dish, place a layer of eggplant slices, and cover with tomato sauce. Repeat the process until all the ingredients are used.
4. Add the Parmesan and mozzarella slices, then cover with breadcrumbs. Bake for 30 minutes.