1-First Step: Preheat and Prep the Eggplant Begin by preheating your oven to 400 degrees F and setting the racks in the upper and lower thirds. Lightly coat two rimmed baking sheets and a 9×13-inch baking dish with nonstick spray. Arrange your eggplant slices in single layers on the baking sheets, trimming any outer curves so they lie flat. Brush both sides with 2 ½ tablespoons olive oil, then sprinkle on ½ teaspoon kosher salt and ¼ teaspoon black pepper.

2-Second Step: Roast the Eggplant Roasting the eggplant slices until they’re soft and golden, which takes about 25 minutes. Remember to flip the slices and swap the pans halfway through for even cooking. Once done, reduce the oven temperature to 350 degrees F. This step is crucial for eggplant lasagna as it removes excess moisture and brings out a caramelized flavor that makes the layers so tasty.

3-Third Step: Sauté the Mushrooms and Sauce In a large skillet, heat the remaining ½ tablespoon olive oil over medium heat. Add the 16 ounces of sliced cremini mushrooms and sauté them until soft, about 7 minutes. Stir in the 3 cloves of minced garlic, the remaining ½ teaspoon kosher salt, and ½ teaspoon dried oregano, cooking for another 2 minutes. Remove from heat and mix in the 24-ounce can of marinara sauce. This creates a flavorful base that’s adaptable for various dietary tweaks.

4-Fourth Step: Mix the Ricotta Filling In a large bowl, combine the 15-ounce container of part-skim ricotta cheese with ¼ cup grated Parmesan cheese, 1 large egg, the remaining ½ teaspoon kosher salt, and ¼ teaspoon black pepper. Mix it all well, then fold in the 10-ounce package of thawed and squeezed spinach. This filling adds a nutritious boost and helps the eggplant lasagna hold its shape.

5-Fifth Step: Assemble the Lasagna Spoon half of the mushroom marinara sauce into your prepared baking dish and spread it evenly. Layer on 4 eggplant slices, followed by all the ricotta mixture. Add another 4 eggplant slices, then the rest of the marinara sauce. Top it off with 1 cup shredded part-skim mozzarella cheese and the remaining ¼ cup grated Parmesan cheese. For a vegetarian twist, you could swap mushrooms for other veggies here.

6-Final Step: Bake and Serve Bake the assembled eggplant lasagna for 25-30 minutes until the cheese melts and everything is hot and bubbly. Take it out of the oven, sprinkle on 2 tablespoons of chopped fresh herbs, and let it rest for 5-10 minutes before serving. This rest time lets the flavors settle, making your eggplant lasagna easier to slice and even more enjoyable.