Use the highest quality extra virgin olive oil you have available, as it provides the primary flavor profile for this entire dish. Slice your garlic as thinly as possible using a mandoline or sharp knife to ensure it toasts evenly without burning. Cook your pasta one minute less than directed on the box so it can finish absorbing the flavorful liquid in your skillet. Never skip the reserved pasta water; its starch is the secret ingredient for emulsifying the sauce properly in this Spaghetti Aglio Olio With Zucchini Recipe. Keep the heat on medium-low when infusing the oil with garlic to prevent harsh burnt flavors from ruining the final profile.