Stir into sauce; continue to simmer. In a shallow bowl, whisk together eggs and buttermilk. Place breadcrumbs in another bowl. Slice eggplant around 1/4-inch thick and dip each slice into egg ...
Top with another layer of the remaining eggplant, followed by the remaining sauce and then the remaining mozzarella and Parmesan. Bake until browned on top, 25 to 30 minutes.