Eggplant and Walnut Pastitsio with Olive Oil and Yogurt Béchamel

Pastitsio didn’t enter my pantheon of dishes, ironically, until it left Greece. Faye Levy’s recipe for Macaroni and Eggplant Kugel, on the Jerusalem Post website, helped me to reinvent a Greek classic as a simple and vegetarian pastitsio. She suggests making the béchamel together with the sautéed onions, which leaves one less pan to clean. But more important, Levy suggests baking the dish in a bain-marie, which creates a creamy and moist pastitsio, a far c