Vanilla extract comes from the pods of the Mexican flat-leaved vanilla plant (Vanilla planifolia) and is one of the most expensive spices worldwide, alongside saffron. Indeed, producing vanilla and vanilla essential oil is extremely labour-intensive because the flowers must be hand-pollinated and the bean pods require ripening, drying, and conditioning to create their characteristic flavour and aroma. 

https://www.nationalnutrition.ca/aromatherapy-essential-oils/single-essential-oils/vanilla-oil.html