6 to 8 baby Idaho® Yukon Gold potatoes (any long and narrow waxy heirloom will work), based on skillet size
8 tablespoons unsalted butter, melted
4 garlic cloves, minced
4 tablespoons finely minced herbs (I use parsley, rosemary, and thyme.)
4 tablespoons grated Parmesan (optional)
salt and pepper, to taste
Preheat oven to 425º F. Scrub the potatoes thoroughly and remove all the hard bits from the skin, as the skins will be left on.
Slice one thin layer off each potato, along the length, then set aside. This serves as a solid base to rest on while you slice them. Place a potato flat side-down and use a sharp knife to make slices that are about ⅛-inch apart; slice into the potato but not completely through it -- the slices should stay connected at the bottom. (Tip: Place a chopstick on either side of the potato so that you hit the chopstick before slicing all the way through.)
Carefully fan out the sliced pieces without breaking them apart. Repeat with each potato.
In a small mixing bowl, combine the melted butter, garlic, and minced herbs. Set aside.
Using a pastry brush, brush the bottom and sides of a cast iron skillet and each potato with the garlic-herb butter mixture. Brush the potatoes generously, making sure to get in-between each slice. Reserve ⅓ of the garlic-herb butter for basting.
Nestle the potatoes into the skillet. Sprinkle with Parmesan cheese (if using) and salt and pepper, to taste. Bake for 1 hour, basting the potatoes every 15 minutes with the remaining garlic-herb butter, or until tender on the inside and crisp on the outside.