4 medium zucchini (about 2 pounds)
3 tablespoons extra virgin olive oil
1 tablespoon minced garlic (3 to 4 cloves)
1/4 to 1/2 teaspoon crushed red pepper flakes, depending on how spicy you like the pasta
2 medium tomatoes, chopped, see note (about 12 ounces)
1/2 cup shredded parmesan cheese, plus more for serving, see notes for alternatives
1 cup basil leaves, torn into pieces
1 teaspoon cornstarch
2 teaspoons cold water
Salt, to taste