Add simple syrup and several mint leaves to the a cocktail shaker. Muddle gently to release mint essence.
Add bourbon and ice to the shaker and shake for 10-15 seconds.
Pour over a cup filled with ice. Garnish with more fresh mint.
Notes
Muddle - Use a muddler tool to muddle the mint leaves, which releases a minty essence and flavor into your cocktail. You can do this in your cocktail shaker as well as the bottom of your julep cup for maximum minty essence.
Julep Cup - While you can certainly enjoy a Mint Julep in any short glass, the experience is elevated by the silver julep cup. Much like a Moscow Mule is served in a copper mug, the silver julep cup has become ubiquitous with this recipe.
Peppermint vs. Spearmint - There are many varieties of mint available and if you have access to more than one we have heard that spearmint is the preferred ingredient. If you have access to both, do an A/B and let us know which one you enjoy more. There are also many more varieties of mint (apple mint, chocolate mint, strawberry mint, etc). If anyone wants to take this journey for research purposes, we support you.
Simple Syrup Substitutes - If you like, you can use honey simple syrup or mint simple syrup for a slight variation. You can also use maple syrup or agave as a substitute.