Saffron has the distinction of being the world’s most expensive spice by weight. It is actually the red stamens of a purple crocus flower, and it takes about 5,000 flowers to produce an ounce of saffron. Thankfully, the amount needed in the average recipe is so small that it is affordable to use. In this elegant sauce the cream takes on the flavor of the saffron and the zucchini. It is perfectly suited to the delicate flavor and texture of egg pasta.