Thinly slice the potatoes with a knife or mandolin and set them aside.
Butter the cast iron skillet and then place the potato slices vertically filling the skillet.
Pour the melted butter over the potatoes and sprinkle the minced garlic, panko and then the parmesan cheese. Season with salt and place in the oven to bake for about an hour until the potatoes are crispy.
Take out and let cool for 10 minutes. Top with more fresh grated parmesan cheese and chopped parsley.