Step 1: Roast Eggplant : Preheat oven to 400°F (200°C). Toss diced eggplant with 2 tablespoons olive oil, salt, and pepper. Spread on a baking sheet and roast for 20 minutes, flipping halfway, until golden and tender.
Step 2: Cook Pasta : Bring a large pot of salted water to a boil. Cook rigatoni according to package instructions until al dente. Drain and set aside, reserving 1/2 cup pasta water.
Step 3: Prepare Tomato Sauce : In a large skillet, heat 1 tablespoon olive oil over medium heat. Sauté onion for 3-4 minutes until translucent. Add garlic and cook for 1 minute. Stir in crushed tomatoes, oregano, red pepper flakes, and sugar if using. Simmer for 10-12 minutes, stirring occasionally.
Step 4: Combine Pasta and Sauce : Add roasted eggplant to the tomato sauce and stir gently. Toss in cooked rigatoni, adding reserved pasta water a little at a time to coat the pasta evenly. Stir in chopped basil.
Step 5: Finish and Serve : Transfer pasta to serving plates. Sprinkle generously with ricotta salata and drizzle with extra olive oil. Serve hot.