Old Fashioneds are easy to store in bulk and convenient for pouring late at night. In fact, many restaurants batch them to make serving quick and easy. To make ahead, make a large batch of simple syrup and multiply the recipe by the amount of drink you want to make. For example, a batch of 8 cocktails would be 4 ounces of simple syrup, 4 teaspoons of bitters, and 16 ounces of bourbon. Mix the liquids and store in an airtight container until ready to eat, pour over ice and garnish.
Simple syrup can be made up to a month in advance and stored in an airtight container in the refrigerator. It’s difficult (or even impossible) for him to make a single serving of simple syrup, so he uses about half a cup of syrup. This is enough to make over 10 Old Fashioneds, but you can also use this syrup in coffee, Manhattans, tea, and even baked goods.