Wash parsley, dry and chop the parsley finely. Trim and rinse the zucchini and slice lengthwise in 4 and then again in small segments. Cook the pasta in a pot with plenty of boiling salted water. In a saucepan with oil sauté the peeled garlic; add the zucchini, stirring well, season with a pinch of salt, and let them soften over low heat for 3 minutes; dilute the tomato concentrate with ½ a ladle of water, add it to the zucchini, cover and simmer for 3 minutes or until cooked; blend in the leftover oil and the chopped parsley. Drain the pasta al dente, sprinkle with Parmesan, add the zucchini, stir well and serve immediately.