1. Rinse a chilled Coupe glass with absinthe and dump out remaining liquid. 
2. Place the glass back into the refrigerator to continue chilling. 
3. Add all other ingredients to a cocktail shaker with ice and shake until a frost forms on the shaker.
4. Strain, pour into the chilled Coupe glass.
5. Garnish with a manicured grapefruit twist. 

For the cinnamons simple syrup:

1. In a small saucepan, bring the water and sugar to a boil, stirring until the sugar is dissolved. 
2. Reduce heat and add cinnamon sticks. Simmer for 10-15 minutes. 
3. Remove from heat. Allow the syrup to come to room temperature. Then pour into a container. 
4. Refrigerate. This Cinnamon Simple Syrup will last up to 2 weeks as is in the refrigerator or will last longer if you add a tablespoon of vodka or rum.