Make the sauce. Heat 3 tbs of olive oil, add onion and garlic. Add a can of whole tomato. Crush it with hand. Bring to a simmer and cook over moderately low heat. Till the sauce is very thick, about 25min. Purée until smooth. Season with salt and pepper.
Grill the eggplant slices seasoned with salt and pepper. Drain with pepper towels
1 cup of sauce — eggplant slides — sprinkle some basil —mozzarella and grated parmigiana cheese. Repeat twice. Sprinkle the break crumbs all over at the top. Bake at 400F (200C) for 45 min, until the top is golden and sauce is bubbling. Stand for 15min and serve. This can be premade 1 day before.