In a small bowl, stir together all the spices for cajun seasoning. Store in an airtight container until ready to use.
Preheat oven to 400 degrees. Lightly grease a baking sheet with nonstick spray. Line up drumsticks on the prepared tray.
Sprinkle with cajun seasoning on both sides. Leave the side with the most meat and skin facing up.
Put a dab of about 1/2 tablespoon butter on the top of each drumstick, on the part that is most meaty. The butter will melt all over the meat and skin, keeping the meat juicy, and making the skin crispy.
Bake for 25-30 minutes in the oven until chicken reaches an internal temperature of 165 degrees F.