Preheat the oven to 450º F.

Stir together the butter (or olive oil), rosemary and garlic in a small bowl.

Slice a bottom section off the long side of the potato to create a flat surface. Retain the cut piece. Place the potato flat side down between 2 chopsticks. Hold potato with onion holder. Slice the potato into thin slices using the slats in the onion holder (chopsticks prevent slicing potato through).

Put the potatoes on a baking sheet by placing the cut piece down first and the potato spread open over the top of it.

Brush on the butter mixture, making sure to get in between all the slices. Top with salt.

Bake 30 mins and brush potatoes again with butter mixture. Bake ~30 more mins until tender and crisp.