If preparing homemade marinara, cook it according to its instructions, keeping it warm over low heat if done early. For store-bought sauce, warm it gently over medium-low heat as the pasta cooks. Preheat the oven to 425°F, positioning racks in the upper and lower thirds. Line two large, rimmed baking sheets with parchment paper for easy cleanup. Using a vegetable peeler, remove long alternating strips of the eggplant skin to create a striped effect, then cut the eggplants into ½-inch thick rounds, discarding the ends. Arrange the slices on the prepared baking sheets, brushing both sides with olive oil and seasoning with the salt and plenty of black pepper. Roast the eggplant until deeply golden and tender, about 35–45 minutes, turning after 20 minutes, then set aside. Meanwhile, bring a large pot of salted water to a boil and cook the pasta until al dente according to package instructions. Reserve about ½ cup of the pasta water before draining, then return the pasta to the pot. Combine the roasted eggplant with the marinara sauce, adding the remaining teaspoon of olive oil, fresh basil, and red pepper flakes if using. Crush the dried oregano between your fingers as you sprinkle it in. Fold the cooked pasta into the sauce along with a few tablespoons of the reserved pasta water. Incorporate about two-thirds of the grated cheese, reserving the rest for garnish, and adjust seasoning with more salt and pepper as needed. If the sauce appears too thick, loosen it with a bit more pasta water. Portion the pasta into four bowls, topping each with the remaining cheese and extra basil leaves. For additional richness, drizzle with a touch of olive oil. Store leftovers covered in the refrigerator for 4 to 5 days.