Preheat your Spark grill to 500˚F, or preheat a regular grill to medium heat.
In a large bowl, toss the potato slices with the olive oil and granulated garlic. Season well with salt and pepper.
Clean and oil the grill grates. Arrange the potatoes in a single layer on the grill. Cover and cook until they’re lightly browned with grill marks on the bottom, about 6-8 minutes. Flip the potatoes over and rearrange them on the grates. Cover and continue cooking until the potatoes are caramelized on the other side and are tender in the center, about 5-6 minutes longer—don’t be afraid to flip and move the potatoes around the grill for even cooking (if you’re using a gas grill adjust the heat as needed so that the potatoes don’t darken too quickly).
Transfer the grilled potatoes to a platter and sprinkle lightly with salt. Garnish with grated parmesan cheese and chopped chives, and serve with Herbed Aioli, if you’d like.