Preheat oven to 350. Soak the eggplant in salted water for 15 minutes. Drain well. Put in a large casserole dish, cover with foil bake for 25 minutes or until softened.
Meanwhile, chop the green onions, garlic, and basil in a food processor. Add the coconut cream, mayo, egg, salt and pepper. Process until smooth.
Remove half of the softened eggplant from the casserole dish, leaving one layer. Pour half the basil sauce on top and drop spoonfuls of half the tomato sauce on that. Add the rest of the eggplant and top with the remaining basil sauce and tomato sauce.
Bake uncovered for 20-25 minutes. The edges should be golden and sauce will have thickened.
If you do not need this baked eggplant gratin to be dairy free go ahead and top it with some parmesan and mozzarella cheese. It is fabulous either way.