Preheat oven to 400 degrees F. Place the eggplant rounds on a baking sheet and brush with olive oil. Roast for 20 minutes or until lightly golden.
Meanwhile, heat the remaining olive oil in a large skillet over medium heat. Add the onion and garlic and cook until softened, about 5 minutes. Add the oregano, cinnamon, cumin, nutmeg, cloves, salt, and pepper and stir to combine. Cook for an additional 2 minutes.
In a medium bowl, combine the ricotta, Parmesan, and mozzarella cheeses. Add the cooked onion mixture to the cheese mixture and stir to combine.
In a medium saucepan, melt the butter over medium heat. Whisk in the flour and cook, stirring constantly, for 2 minutes. Gradually whisk in the milk and bring to a simmer. Cook, stirring constantly, for 5 minutes or until thickened. Remove from heat and stir in the Parmesan cheese.
Spread half of the cheese mixture in the bottom of a 9x13-inch baking dish. Top with the roasted eggplant slices and then the remaining cheese mixture. Pour the béchamel sauce over the top.
Bake for 25 minutes or until golden and bubbly. Let stand for 5 minutes before serving.
Interesting Facts
Pastitsio is a traditional Greek dish that is often served as a main course.
Eggplants are a great source of dietary fiber, vitamins, and minerals.
Béchamel sauce is one of the “mother sauces” of French cuisine.