- 5 tablespoons goose or duck fat
- 1/2 stick (1/4 cup) unsalted butter
- 1 1/2 teaspoons salt
- 1/4 teaspoon black pepper
- 3 lb boiling potatoes (4 to 5 large)
- 1 tablespoon finely chopped fresh flat-leaf parsley
- 1 teaspoon minced garlic
- Special equipment: a well-seasoned 10-inch cast-iron skillet; a Japanese Benriner or other adjustable-blade slicer; a 9 1/2-inch round of parchment paper
- Put oven rack in middle position and preheat oven to 400°F.
- Melt fat and butter in cast-iron skillet over low heat. Remove from heat and pour into a large bowl. Do not wipe skillet.
- Mix salt and pepper in a small bowl. Peel potatoes and, working over bowl of fat, cut crosswise into 1/16-inch-thick slices, letting them fall into fat, then toss to coat. Arrange one third of potatoes in 1 layer in skillet in overlapping concentric circles. Sprinkle with one third of salt mixture, then make 2 more layers of potatoes in same manner, seasoning each layer with one third of salt mixture. If there is any fat remaining in bowl, scrape onto potatoes.
- Cook potatoes over moderate heat 15 minutes. Press down on potatoes with a wide metal spatula, then cover surface with parchment paper and cover skillet with foil.
- Bake until outside edge is golden brown and potatoes in center are tender when pierced with a fork, about 25 minutes. Let stand, covered, at room temperature 5 minutes, then carefully loosen edge with a heatproof flexible spatula. Invert a plate with a rim over skillet. Using pot holders and holding plate and skillet together firmly, invert skillet. Remove skillet and sprinkle potato cake with parsley and garlic.