Preheat the oven to 375˚ F. Lay the eggplant slices out on baking sheets in a single layer. Brush lightly with olive oil, season with salt and pepper, flip and repeat on the other side of all the slices. Roast, flipping halfway through the baking time, until slightly soft and golden brown, about 35 minutes total. Increase the oven temperature to 400˚ F.
Spoon 1¼ cups of the tomato sauce in a large deep sauté pan. (A casserole dish works just as well.) Layer half of the eggplant slices evenly in the pan. Sprinkle with a third of the grated Parmesan and half of the mozzarella. Spread another 1 cup of sauce over the cheese, the remaining eggplant slices, another third of the Parmesan and the remaining mozzarella. Top with the remaining Parmesan. Bake for about 30-35 minutes or until the cheese is browned and bubbling.
Remove from the oven and let cool 15 minutes. Garnish with fresh basil and serve warm.
