Closely related to cinnamon, Cassia has a strong, spicy aroma that can be used in small amounts to transform any essential oil blend. Cassia essential oil has been used for thousands of years for its many wellness benefits. It is one of the few essential oils mentioned in the Old Testament. doTERRA Cassia is a warming oil and can be used in cooking as a cinnamon substitute in pies and breads, or alone in a variety of dishes and desserts.