Always use high-quality, cold-pressed extra virgin olive oil because the oil is a primary flavor component of the Spaghetti Aglio Olio With Zucchini Recipe. Cut your garlic into thin, uniform slivers so they crisp up at the same rate without turning bitter in the hot oil. Reserve more pasta water than you think you need to thin out the sauce if it becomes too tacky after sitting. Toss the ingredients over medium heat to maintain the emulsion, which is the secret to a professional Spaghetti Aglio Olio With Zucchini Recipe. Add the parsley at the very last second to preserve its bright, herbaceous flavor and vibrant green color.