Preparation

• Position racks in the upper and lower thirds of your oven. Preheat the oven to 400 degrees F. Lightly coat 2 rimmed baking sheets and a 9x13-inch baking dish with nonstick spray.
• Arrange sliced eggplant in a single layer on the sheet pans. Brush 2 ½ tablespoons of the oil over both sides and sprinkle with ½ teaspoon kosher salt and ¼ teaspoon pepper.
• Roast the eggplant for about 25 minutes, flipping the slices halfway through, then reduce the oven temperature to 350 degrees F.
• In a large skillet, heat the remaining ½ tablespoon oil over medium heat. Add sliced mushrooms and sauté until softened, about 7 minutes. Stir in garlic, ½ teaspoon kosher salt, and oregano; cook for another 2 minutes.
• Remove from heat, add marinara sauce, stir to combine.
• In a large bowl, mix ricotta, ¼ cup Parmesan, egg, remaining salt, and pepper until smooth. Stir in spinach.
• Spread half of the mushroom sauce on the bottom of the baking dish. Layer with 4 eggplant slices, the ricotta mixture, another 4 slices of eggplant, and top with remaining mushroom sauce. Finish with mozzarella and remaining Parmesan.
• Bake for 25 to 30 minutes until cheese is melted and bubbly. Remove, sprinkle with fresh herbs, and let rest for 5 to 10 minutes before serving.