Step 1

Bring 1 cup water and 1 cup granulated sugar to a boil in a small saucepan. Stir until the sugar dissolves. Submerge 1 cup tightly packed mint leaves in the liquid. Remove the pan from the heat, cover, and infuse for 1 hour. Strain the syrup through a fine-mesh strainer into a clean, lidded jar. Refrigerate if not using immediately.

Step 2

Drop 1/4 cup loosely packed fresh mint leaves into the bottom of a pitcher. Muddle using a wooden spoon to release the mint's essential oils by pressing down and slightly twisting your utensil. The mint should appear bruised but not torn or blackened. Stir in 30 ounces bourbon and mint simple syrup.

Step 3

Wrap ice cubes in a clean tea towel. Pound with a rolling pin or meat mallet to crush the ice.

Step 4

Scoop enough ice into individual julep cups or Old Fashioned glasses until they are very full. Pour in 3 ounces of the bourbon and mint syrup mixture. Top with a splash of sparkling water. Garnish with a sprig of mint and a dusting of powdered sugar, if desired