Spices derive their flavors from essential oils that evaporate over time, so they need to be replaced periodically. If stored in tightly closed containers in a cool, dark place, ground spices will last for about 6 months and whole spices will last for about 1 year. Purchase spices in small amounts from stores with high turnover. For the most pronounced flavor, use whole spices and grind them just before using. To grind the cinnamon for this recipe, in a small fry pan over medium heat, toast part of a cinnamon stick until fragrant, then break up the stick and grind in a mortar with a pestle or in a spice grinder.