Preheat oven to 350 degrees F. Spray a baking dish lightly with oil spray. Set aside.

For eliminating the bitter flavor from eggplants, sprinkle with salt and let them sit for 20 minutes. Then rinse well to remove the salt and pat dry.

To prepare the stuffing, cut the eggplants lengthwise, into 3/4-inch thick slices.

Heat the oil in a non-stick skillet over medium heat. Fry the eggplants until golden brown (do not add too much oil). Place them on a paper towel to absorb the extra oil.

Using a potato masher, mash the eggplants until slightly smooth. Add the garlic, walnuts, and basil. Season with salt. Mix well and set aside.

To prepare the tomato cups, carefully cut tops off of each tomato and scoop out seeds and pulp with a melon baller or spoon. Reserve the tops.

Stuff the tomatoes with the eggplant mixture and place in the baking dish.

Bake until they start to soften and skins begin to wrinkle (but still hold their shape), about 20-22 minutes.

Remove from the oven and top each with mozzarella cheese.

Place the tomato tops to the baking dish (not on top of the tomatoes). Broil until cheese is melted and lightly golden.

Put the tomato tops on them. Serve hot.