2 tablespoons extra-virgin olive oil
2 small onions, halved and thinly sliced
3 cloves garlic, grated
Kosher salt
1 1/2 teaspoons red pepper flakes
1 1/2 teaspoons sugar
One 28-ounce can plus one 15-ounce can whole San Marzano plum tomatoes
1 medium eggplant (about 1 1/4 pounds), sliced into 1/2-inch-thick rounds
Kosher salt
1/4 cup all-purpose flour
Freshly ground pepper
3 large eggs
1 1/2 tablespoons whole milk
2 cups Italian-style breadcrumbs
1 1/2 teaspoons dried oregano
1 1/2 teaspoons fresh thyme leaves
Vegetable oil, for frying (1 1/2 to 2 cups)
12 ounces fresh mozzarella cheese, thinly sliced
1/4 cup grated Parmesan cheese (about 1 ounce)
2 cups grated provolone cheese (about 8 ounces)
Handful of fresh basil leaves, torn