3 large potatoes, or 6 small
1/3 cup unsalted butter, melted
Freshly ground black pepper
Preheat the oven to 425°.
Using a mandolin, slice the potatoes very thinly. As you are slicing them, transfer to a bowl of cold water to prevent browning. Transfer the potatoes sliced to towels and pat them dry.
Generously brush the bottom of a cast iron skillet with melted butter. Arrange the slices of potatoes in concentric circles, overlapping them until the bottom of the skillet is covered. Season with salt and pepper.
Continue with more potatoes, melted butter, salt and pepper until you have layered all of the potatoes. Cover with a tent of aluminum foil.
Place in the oven and bake for 30 minutes. Uncover the skillet and continue cooking for another 20-25 minutes, or until the potatoes are tender and a golden brown. Allow to cool for 10 minutes.
Turn the potatoes out onto a platter or cutting board. Slice as you wish!