Add cognac, pear syrup and bitters to a mixing glass w/ ice; stir until chilled. Strain into a chilled old fashioned glass containing a large chunk of ice. Grate cinnamon across the top, and garnish with a pear fan.
Pear syrup: juice 2 whole d'anjou pears (do not remove the skin). Strain thoroughly until clarified. Add 1/2 cup of pear juice to a pot along with 1 cup of granulated sugar; simmer until combined and clear. Remove from heat, add the remaining 1/2 cup of pear juice and incorporate until uniform. Strain again, bottle and chill until needed.