In a small saucepot, heat 1/4 cup of water and the sugar to a boil. Remove from heat and drop in the mint leaves. Steep 5-10 minutes. Discard the solids and let cool.
Measure 1-2 tablespoons (or more, depending on how sweet you want your drink) of syrup in the bottom of a tall glass, then the sparkling water. Add ice, then pour the espresso overtop. Be mesmerized as the espresso slowly trickles down to the bottom of the cup.
Add cream or milk as desired and top with fresh mint sprigs.
Notes
*Espresso: If you do not have an espresso machine, you can use 1/2 cup very strong brewed coffee as a replacement, but you will not have the crema layer and the taste will differ.