Preheat the oven to 475°F / 240°C. Cut 800g of eggplant into 1in / 2.5cm cubes. Measure 4 tablespoons of olive oil, 1 teaspoon of salt, and 1 teaspoon of black pepper.
Toss the eggplant with half the measured oil, salt and pepper. Spread over lined baking sheets without crowding. Roast for 20 minutes, turn and roast for 5 minutes more. Leave on the baking sheets.
Cook 300g of rigatoni in boiling salted water until al dente, then drain.
Meanwhile, heat the remaining oil over medium heat. Stir 2 minced garlic cloves for 20 seconds, then cook ½ finely chopped small onion for 2-3 minutes.
Add ¼ cup of dry white wine and simmer until mostly evaporated. Add 700g of passata, ¼ cup of water, 1 teaspoon of dried oregano and the remaining salt and pepper. Simmer for 5 minutes.
Gently fold in the eggplant, pasta and ½ cup of chopped basil. Serve with grated Parmesan.
