Add olive oil, sliced onion and tomato sauce to a small pot, bring to a simmer over low heat and allow to cook, stirring occasionally, until it has reduced to about ⅓ of its volume. Set aside when it has finished cooking.
When ready to fry, heat the oil in a 10-inch skillet, over medium heat, until the oil is hot enough to make a piece of the zucchini sizzle rapidly as soon as it hits it. While the oil is heating, thoroughly pat the zucchini dry. Fry the zucchini in batches, until golden. With a slotted spoon or skimmer, transfer the fried zucchini to paper towels to drain.
Fill a large pot with water for the pasta. Bring to a boil over high heat. Once the water starts to boil for the pasta add a small handful of salt to the water and bring to a rolling boil. Add the pasta and cook until al dente. When the pasta is perfectly al dente drain the pasta. Spoon some of the sauce into a bowl and add the pasta, the eggplant and about half of the ricotta salata, toss it all together adding more tomato sauce as you stir.
Serve immediately with a few basil leaves and the rest of the grated ricotta salata.
