Brush the eggplant with the oil and arrange the rounds in a single layer, or slightly overlapping at the edges, on a large baking sheet (or two, if necessary). Sprinkle with ¼ teaspoon of the salt. Roast until tender, 12 to 15 minutes. Remove from the oven but leave the oven on.
Meanwhile, crumble the tofu into a large bowl with the remaining ½ teaspoon salt and the pepper. Combine well. Stir in the mozzarella and ricotta until well mixed.
Cover the bottom of a 9 x 12-inch baking dish with ¾ cup of the marinara sauce. Top with half the basil, then half the roasted eggplant, half the zucchini, and half the mozzarella mixture. Repeat by topping with another ¾ cup of the marinara sauce and the remaining basil, eggplant, zucchini, and mozzarella mixture.
Top with the remaining tomato sauce and sprinkle evenly with the Parmesan
Roast until the eggplant is soft, the casserole is bubbling throughout, and the Parmesan is golden brown on top, about 30 minutes. Serve warm.
This recipe can be made with vegan cheeses or with cheese not made with animal enzymes.