Add all the ingredients to a shaker with ice and shake.
Strain into an ice-filled Collins glass.
Top with the soda water.
Garnish with a lime wheel and freshly grated nutmeg.
*Cinnamon syrup: Mix 1 cup sugar and 1 cup boiling water, stirring until the sugar is dissolved. Add 5 cinnamon sticks, remove from heat, and let sit for 2 hours. Pour into a jar, and let cool. Keeps refrigerated for up to 3 weeks.