Cut the mozzarella into round slices, grate the cheese. Cut the eggplants into long slices, sprinkle with salt and leave them for 15 min. Then smear them with olive oil and bake in a 392°F (200 °C) oven until softened.
Prepare a tomato sauce by parboiling the tomatoes with hot water, peeling them and cutting them finely, then blending. Combine the tomatoes with the tomato paste, finely chopped basil and remaining salt. Boil the sauce on medium heat until slightly thickened.
In an oven dish smeared with olive oil, arrange a layer of eggplants, place the sliced champignons on top and pour on half the tomato sauce on top.
Sprinkle with half the grated cheese and half the mozzarella. Then place eggplants, mushrooms, tomato sauce, mozzarella once again and sprinkle with the remaining cheese. Bake 25 min. at 392°F (200 °C).