Look for a flat side on the potato and place the potato, flat side down, on a cutting board. If the potatoes do not have a flat side, make one by removing some of the potato with the sharp knife.
Place two chopsticks on the sides of the potato. They should sit snugly along the sides of the potato.
Use a sharp knife to cut the potato crosswise into ⅛-inch thick slices, stopping when your knife reaches the chopsticks. This way, the potatoes will stay intact at the bottom.
Repeat with the remaining potatoes.
Bake the potatoes:
Preheat oven to 425°F. Line a baking sheet with parchment paper.
Place the potatoes on the baking sheet. Brush each potato with melted butter.
Season the potatoes with salt and pepper. Use your hands or a brush to coat the potatoes well on the sides and between the potato slices. Bake the potatoes for 40 minutes.
Remove them from the oven and sprinkle them with Parmesan cheese. Continue baking for 20 minutes.
Serve:
Serve potatoes warm.
Notes
For some extra flavor, you can use herbed butter. Also, you can combine garlic with the butter and red pepper flakes and use this mixture to brush the potatoes.