Pour bourbon into a 16-ounce mason jar or two 8-ounces mason jars.
Insert cinnamon sticks and cloves. For less spice, use fewer whole spices.
Store in a dark place. Smell and taste it every 2-3 days until it reaches your preferred level of spice. More time and more spices will yield a stronger taste.
Notes
If the cinnamon whiskey becomes too strong in flavor, you can dilute it with more whiskey, preferably the same brand/type you started with.Don't add more than 2 cloves, as they can overpower the cinnamon. Cloves have numbing properties that can be unpleasant to drink.