To make Cinnamon Simple Syrup, mix sugar, water and cinnamon sticks in 1-quart saucepan. Heat to boiling over medium-high heat, stirring until sugar is dissolved. Remove from heat; set aside 1 hour to cool. Discard cinnamon sticks. Pour syrup into glass jar. Cover jar, and refrigerate until needed. Makes 1 1/4 cups.
To prepare cocktail, fill cocktail shaker with ice. Add 1 ounce cinnamon simple syrup, vodka, half-and-half and creme de cacao; cover and shake. Strain into cocktail glass. Sprinkle with cinnamon-sugar.