Spaghetti and Eggplant Meatballs

Name: Spaghetti and Eggplant Meatballs
Ingredients: 1 large eggplant (1 pound), cut into ½-inch-thick rounds; 3 tablespoons extra-virgin olive oil, plus more for drizzling; 1 teaspoon minced garlic; 1 ½ teaspoons minced fresh oregano; 1 cup white beans, such as cannellini (from a 15.5-ounce can), drained and rinsed; 1 large egg, lightly beaten; ½ cup panko breadcrumbs; 1 ounce Parmigiano-Reggiano, grated (¼ cup), plus more for serving; ¼ teaspoon red-pepper flakes, plus more for serving; Kosher salt; 3 ½ cups All-Purpose Tomato Sauce; 12 ounces spaghetti