Fried Pancake of Grated Potatoes (Pommes Paillasson)

Preparation Peel potatoes and grate in a food processor fitted with coarse-shredding disk. Working in small batches, wrap potatoes in a kitchen towel, then twist and squeeze to remove as much liquid as possible. Transfer to a bowl. Heat 3 tablespoons butter in a 12-inch nonstick skillet over moderately high heat until foam subsides. While butter heats, toss potatoes with salt and pepper. Reduce heat to moderate, then immediately spread potatoes in skillet, pressing top down once with a spatula. Cook potato cake until golden brown on underside, about 12 minutes. Slide cake onto a large plate. Heat remaining 2 tablespoons butter in skillet over moderate heat until foam subsides. Invert cake onto another plate (golden side up), then slide cake back into skillet. Cook cake until underside is golden brown, about 12 minutes. Slide cake onto a cutting board and cut into 6 wedges.