To make the sauce, heat the olive oil in a deep pan. Add the garlic and saute 2-3 min. Add the tomatoes, oregano and bring the mixture to a boil.
Lower the heat and saute on a low stove for 30-40 min. Sprinkle with salt. Heat the oven to 446°F (230 °C).
Put the eggplants that have been cut into slices and drained of the bitterness in a tray, sprinkle with olive oil and salt and bake for 10 min. Flip them over and bake another 10 min.
Lower the heat to 428°F (220 °C). Arrange 1/3 of the eggplants in another baking dish and sprinkle with the tomato sauce, mozzarella, oregano and parmesan.
Repeat this process, topping off with tomato sauce and parmesan. Distribute the finely chopped butter. Bake about 35 min.