A pinch of cayenne pepper adds just the right amount of heat in this fragrant cocktail syrup made with cinnamon, cardamom, and vanilla beans. Bottle it for holiday or hostess gifts or use it to make our Spiced Hot Buttered Rum.
Combine sugar, cardamom, and cinnamon in a medium saucepan. Split vanilla beans lengthwise and scrape out seeds; add seeds and beans to sugar mixture with 4 cups water. Bring to a simmer over medium-high, stirring until sugar is dissolved (if it begins to boil, reduce heat -- boiling will make the syrup cloudy). Remove from heat; add cayenne. Let steep 1 hour.
Strain through a fine-mesh sieve into a large liquid-measuring cup; discard cardamom pods but reserve cinnamon sticks and vanilla beans. Refrigerate until completely cool, 1 hour. Pour into gift bottles; divide reserved vanilla beans and cinnamon sticks among bottles. Syrup can be stored in bottles, refrigerated, up to 1 month.