Meanwhile, heat the 3 tablespoons of oil in a large saucepan. Add the garlic and cook over moderately high heat, stirring, until soft but not brown, about 1 minute. Add the sliced zucchini, season with salt and pepper and cook, stirring often, until very tender but not falling apart, abut 12 minutes. Fold the zucchini into the pasta along with the basil, ricotta and 1/2 cup of the Parmesan. Season with salt and pepper and toss to combine. Drizzle in olive oil to taste. Transfer the pasta to shallow soup plates, sprinkle with the remaining 1/4 cup of Parmesan and serve.