In a julep cup or glass, muddle the mint sprigs with the simple syrup until the mint is well crushed and the aroma is released.
Fill the cup with crushed ice and pour in the bourbon.
Stir until the outside of the cup is frosted.
Top with additional crushed ice and garnish with a mint sprig.
Notes
Note: If you don't have a Julep cup, you can use any glass, but the traditional silver or pewter Julep cup helps keep the drink extra cold. (Or order these.) Also, if you don't have simple syrup, you can make it by dissolving sugar in equal parts water over low heat until the sugar dissolves.