Rinse the potatoes to remove dirt and debris. Pat dry with a paper towel.
On a cutting board, use a sharp knife to cut thin slices perpendicular to the length of the potato 3/4 of the way deep. Do not cut all the way through.
Drizzle the potatoes in oil, and place them in the air fryer basket. Be sure the bottom of the potato (where it's not cut) is sitting on the air fryer basket so the sliced part of the potato will crisp up. Sprinkle salt, pepper, and garlic powder.
Cook in the air fryer at 400° for 10 minutes. When done, the potatoes will shrink in size and the slices will open slightly.
In a saucepan, melt butter and then brush on potatoes. Coat inside the slices well.
Cook in the air fryer another 5-8 minutes until fully cooked. Potatoes should be crispy on the outside edges, but tender enough for a fork to go through. h
Remove potatoes and plate. Add your favorite toppings like bacon bits, sour cream, chives, green onions, etc. Serve with your favorite main dish.