In a large bowl, combine the vanilla wafers, pecans, 1 cup of powdered sugar, and cocoa powder. Whisk to combine.
In a mixing cup or small bowl, whisk the corn syrup and bourbon together.
Add the corn syrup/bourbon mixture to the dry ingredients and mix to combine.
Place the remaining 2 cups of powdered sugar in a shallow bowl or pie plate. Roll the dough into 1-inch balls, then immediately roll them in the powdered sugar. Set them aside on a baking sheet for 1 hour.
After 1 hour, roll the cookies in powdered sugar again. Store the cookies in an airtight container in the refrigerator.
Notes: I ran the vanilla wafer cookies and pecans through a food processor to ensure that they were finely ground.