This classic French dish can be baked up to eight hours ahead. Let it cool completely, then cover loosely with foil, and refrigerate. To serve, reheat in a 350-degree oven.
- 6 medium russet potatoes (2 3/4 pounds total), peeled
- 6 tablespoons butter, melted
- Coarse salt and ground pepper
Preheat oven to 450 degrees. Using a food processor with a slicing blade or a sharp knife, slice potatoes as thinly as possible, 1/4 inch thick or thinner. (Do not place sliced potatoes in water; the starch is needed to bind the layers.).
Brush bottom of a 10-inch cast-iron skillet with 1 1/2 tablespoons butter. Starting in center of pan, arrange potato slices, slightly overlapping, in circular pattern, covering surface. Brush with another 1 1/2 tablespoons butter; season well with salt and pepper. Repeat for two more layers.
Place over high heat until butter in pan sizzles, 2 to 4 minutes.
Transfer to oven; bake until potatoes are fork-tender, about 1 hour. Remove from oven. Run a small spatula around edges of potatoes; slide large spatula underneath potatoes to loosen. Carefully invert onto a plate, and cut into wedges.