Baked Eggplant with Mushroom and Tomato Sauce

1 eggplant, peeled, cut into 1/4-inch-thick slices (about 1 1/4 pounds)
Cooking spray
1 c onion, chopped
1/2tsp dried Italian seasoning
1/4tsp kosher salt
2 cloves garlic, chopped
1 pack mushrooms,(8-oz)sliced
1/4tsp black pepper, divided
1 can tomato sauce,(8-oz) divided
2/3c mozzarella cheese, shredded, divided
Parmesan cheese, grated

Preheat broiler. Arrange the eggplant slices on a baking sheet coated with cooking spray, then broil 3 minutes on each side or until lightly browned. Preheat oven to 375°. Heat a large nonstick skillet coated with cooking spray over a medium heat, and add onion and next 4 ingredients (onion through mushrooms). Cover and cook 7 minutes or until tender, stirring the mixture occasionally. Increase the heat to medium-high, uncover and cook for 2 minutes or until the liquid evaporates. Spread half of the mushroom mixture in the bottom of a 1 1/2-quart round baking dish coated with cooking spray. Arrange half of eggplant slices over the mushroom mixture, and sprinkle with 1/8 teaspoon of pepper. Top with 1/2 cup of tomato sauce and 1/3 cup of mozzarella. Spread remaining mushroom mixture over the mozzarella, then top with remaining eggplant slices. Sprinkle with 1/8 teaspoon of pepper, and top with remaining tomato sauce. Cover and bake at 375° for 1 hour. Sprinkle with 1/3 cup mozzarella and Parmesan. Bake, uncovered for 5 minutes or until the cheese melts. Let stand for 10 minutes.