Pre-heat oven to 350F.
Peel the potatoes & slice off both ends.
If the potatoes are wider than the width of the muffin tray cups, use the peeler to shave them into cylinders of the same size.
Brush the inside of the muffin tray with melted butter, then combine the remaining butter in a large mixing bowl with the rosemary, garlic, salt & pepper.
Thinly slice into rounds