Prepare your glass by chilling a traditional silver julep cup or double old-fashioned glass in the freezer for about 5 minutes before starting. A properly chilled glass helps maintain the drink’s signature frostiness.
Place mint leaves and simple syrup in the bottom of your chilled glass. If using granulated sugar instead of simple syrup, add a tiny splash of water to help it dissolve.
Gently muddle the mint with the syrup using a muddler or the back of a wooden spoon. Press just enough to release the oils without shredding the leaves—you’re aiming to bruise the mint, not pulverize it.
Add a small amount of crushed ice to the glass, then pour in about half of the bourbon and stir briefly to combine and further chill the mixture.
Fill the glass completely with more crushed ice, creating a mounded dome on top. The ice should be packed tightly to ensure proper dilution and that signature frost on the outside of the glass.
Pour the remaining bourbon over the ice mound, allowing it to gradually filter down through the ice for proper dilution.
Garnish with a generous mint sprig, lightly slapped between your palms first to release its aromatic oils. Position it near the straw so the aroma enhances each sip.
Serve immediately with a short straw, inserted near the mint garnish so the drinker’s nose catches the mint aroma with each sip.