In blender, combine egg, Parmesan cheese, lemon juice, garlic, Worcestershire, salt and pepper. Mix until blended. With the blender on its lowest speed, gradually add oil in a thin stream and continue to blend until dressing is thick and creamy. Pour into jar. Cover and refrigerate for at least one hour. Per the original, "Keeps up five days" -- your risk tolerance may vary.
Let stand at room temperature for fifteen minutes before using. Shake well.