Roasted Eggplant Parmesan

Name: Roasted Eggplant Parmesan
Ingredients: 1 large eggplant (about 500 grams/1 pound); 2 teaspoons kosher salt, plus more for seasoning; One 27-ounce can diced tomatoes (796 milliliters); 2 tablespoons unsalted butter (28 grams); 1 small yellow onion, peeled and halved; 1 small rind of Parmigiano-Reggiano cheese, optional; 2 to 3 sprigs basil; 2 tablespoons olive oil (30 milliliters); Freshly ground black pepper; 1/2 cup finely grated Parmigiano-Reggiano cheese (50 grams); One 4-ounce ball fresh mozzarella (about 125 grams)