Mix sugars and cinnamon in a shallow, wide bowl that is at least the width of the glasses you will be using. Set aside.
Fill shaker halfway with ice.
Slice the mandarins in half and squeeze juice from each half into a shaker. Or juice mandarins to get at least 2 oz of juice. Set aside at least 2 halves.
Add vodka and Cranberry Spice Syrup to the shaker.
Shake!
With the two mandarin halves, use the flesh of the mandarin and drag them along the rim of the glasses. Gently dip the rims into the shallow bowl with the cinnamon and sugar mixtures to create a sugar rim.
Strain half of the contents of the shaker into one glass and the other half into the second glass.
Top each glass off with a splash of soda water if desired.
Cheers!