Peel the eggplpant and cut into large cubes (sprinkle with a little salt and leave for 5 minutes to draw out a little moisture) Pat dry with paper towels and set aside.
Heat the oil in a large frying pan over a medium heat until hot. Add the eggplant in a single layer and fry for 6-7 minutes, turning occasionally. We want a nice brown colour on the eggplant - as it browns and softens, some of the oil will return to the pan.
Remove the eggplant from the pan and set aside. If there is no oil in the pan, add a drizzle to the pan.Add the onion to the pan and fry gently for 2-3 minutes until soft and golden.Now add the garlic and fry for 1 minute to soften.
Add the tomato puree and stir-fry for 20-30 seconds before pouring in all the tomato passata. Add 1 cup of water to the bottle, and shake, then pour into the sauce.Stir in the basil leaves then season with salt, pepper and sugar and stir well. Bring to a simmer then cook gently for 10 minutes (turn the heat down for a gentle simmer).
Return the eggplant to the pan and let this cook for a further 10 minutes. If the sauce reduces too much, add a little water.
Finishing the dish
Cook your chosen pasta in salted water to the packet timings. When cooked, drain (reserving a little of the cooking water).Mix in enough sauce to generously coat the pasta - add a couple of spoonfuls of pasta cooking liquid to loosen the sauce. Arrange in bowls and scatter over the ricotta salata or Parmesan cheese.