Prep: 1. Juice lemons. Make: 1. For each drink, muddle 1 sprig rosemary, 1/4 of the lemon juice, and 1 tablespoon sugar in a shaker or mason jar (use a wooden spoon if you don't have a muddler). 2. Add a few ice cubes and 2 ounces of bourbon put the lid on the shaker/jar and shake thoroughly. 3. Fill your drink glass halfway with ice cubes and then strain in the bourbon rosemary mixture. 4. Top with 2 ounces of ginger ale (or more to taste) and garnish with a sprig of rosemary. 5. Repeat for each drink.
If you prefer, you can make a simple syrup with 1/2 cup water, 1/2 cup sugar and 4 rosemary sprigs. Mix together in a saucepan and bring to a boil for 1 minute, strain, cool and then use 1-2 tablespoons per drink depending on taste.