In a glass, add the mint leaves. Tear any large leaves in half.
Pour in your simple syrup.
Muddle the leaves in the glass to release the mint flavor. The muddling takes a good 2-3 minutes. I used a pestle to do this since I couldn't find my cocktail muddler.
Fill the glass with the crushed ice almost to the top.
Add in your favorite Kentucky bourbon.
Top up with club soda; stir to mix everything together. Garnish with a sprig of mint and enjoy!
This recipe is for a 6 ounce glass. If you're using a 9 ounce glass, use 1.5 ounces simple syrup and 1.5 ounces bourbon.
How to make simple syrup: Add equal parts sugar and water to a small pan (I did 3/4 cup sugar and 3/4 cup water - it makes plenty of syrup). Boil until dissolved; let it cool and transfer to a sealed container (e.g. mason jar) and store in the fridge for up to about a month.