Combine breadcrumbs and Italian seasoning in a shallow dish. Cut tofu lengthwise into 4 steaks and pat dry. Sprinkle both sides of the tofu with garlic powder and salt and then dredge in the breadcrumb mixture.
Heat 2 teaspoons oil in a large nonstick skillet over medium heat. Add onion and cook, stirring, until beginning to brown, about 3 minutes. Add mushrooms and cook until they release their juices and begin to brown, 4 minutes more. Transfer to a bowl.
Add the remaining 1 tablespoon oil to the pan. Add the tofu steaks and cook until browned on one side, about 3 minutes. Turn over and sprinkle with Parmesan. Spoon the mushroom mixture over the tofu, pour marinara over the mushrooms and scatter mozzarella on top. Cover and cook until the sauce is hot and the cheese is melted, about 3 minutes. Sprinkle with basil and serve.