Clean and wash the vegetables well. Cut the zucchini, eggplant (put in separate bowl) and tomatoes into small pieces.

In a separate bowl, sprinkle a little kosher salt over the eggplant and leave for a while so it takes out all of the bitterness.

Peel the garlic and finely chop.

Heat oil in a nonstick skillet. Add eggplant and zucchini, frying well, letting it brown.

Add the tomatoes and basil, garlic. Season up and stir well.

Rub a baking dish with butter (or margarine) (or single ramekins) and place the vegetables inside.

Cover all veggies with with mozzarella and put in preheated 350°F oven for about 20 minutes.

Remove the gratin from the oven and serve at the table.

NOTE: This vegetable gratin is a good complement for steaks or grilled fish. But in a larger proportion is ideal for single-dish main entree if you double the ingredients.