Make your simple syrup by combining equal parts water and sugar in a sauce pan, along with a sprig of the mint leaves. Bring to a boil and simmer until sugar is completely dissolved.

Crush one sprig of mint leaves at the bottom of a glass to release the flavors.

Add simple syrup, rum, and creme de cocoa. Top with soda. Stir to combine.

Garnish with mint leaves (optional).