Preheat oven to 425°F. Spray a large rimmed baking sheet with cooking spray.
Slice each potato in half, then each half into 2 (for smaller potatoes) or 3 (for larger potatoes) wedges, adjust depending on the size of the potatoes. Place into a large mixing bowl.
Drizzle the potatoes with oil, and toss to coat. Add Parmesan, Cajun seasoning, salt and garlic. Mix until evenly distributed.
Place cut side down on pan. Bake for 20 minutes, then turn and continue to bake for an additional 15-20 minutes until fork tender.