1. Combine first 5 ingredients in a large zip-top plastic freezer bag; seal and shake well to combine.
2. Pour buttermilk into a shallow bowl. Dip 2 drumsticks in buttermilk, and place in bag. Seal and shake well, coating drumsticks completely. Place drumsticks on an aluminum foil-lined baking sheet coated with cooking spray. Repeat procedure with remaining drumsticks. Sprinkle remaining cornflake mixture evenly over drumsticks on baking sheet. Lightly coat with cooking spray.
3. Bake at 425° for 25 to 30 minutes or until drumsticks are well browned and done. Serve immediately.