Cut two small slits on each side of the potato. Microwave for 5 minutes, flipping half way through. If you have a larger potato (more than 16 ounces, add 1 additional minute).
Let cool for 10-15 minutes. This will not only make handling the potato easier, but it will help keep the inside of the potato from falling apart during preparation and grilling.
Cut potato in half and place skin side up.
Spray potato with cooking spray. Sprinkle half of the cayenne pepper, salt, pepper, and granulated garlic evenly on the potato skins. Lightly spray potato skins with cooking spray. This will help keep the spices in place and make the potato skin crispy when it cooks.
Flip potato over and repeat step 5.
Grill potato for 20 minutes, flipping half way through. Add butter if desired and enjoy!