To make homemade cinnamon simple syrup add ½ cup granulated sugar and ½ cup water to a small saucepan. Place over medium heat and stir until sugar is fully dissolved. Remove from heat and add in 2 cinnamon sticks. Allow cinnamon sticks to steep for at least one hour, up to 24 hours. Pour into a glass jar and seal tightly. The simple syrup will keep for 1 month in the refrigerator.