This elegant cakelike concoction is made with sliced potatoes, rather than the julienned potatoes used for the straw mat. If you are lucky you have a pommes Anna pan. Its two-piece construction allows you to turn the cake over without spilling the butter out of the pan. In its absence, you can use a nonstick sauté pan, pour off the butter, invert the potato cake onto a plate, and then slide the cake back into the pan, return the butter to the pan, and brown the second side.
1tablespoonbutter, room temperature, plus ¾cup (12tablespoons)
4 large waxy potatoes (about 2½pounds), peeled and shaped into perfect cylinders
Preheat the oven to 400°F. Brush the bottom of a straight-sided 8-inch sauté pan, preferably nonstick, with soft butter. Line the sauté pan with an 8-inch round of parchment paper. Brush the paper with the softened butter. Using a mandoline, slice the potatoes about 1/16inch thick. For a dramatic effect, cut the first two potatoes into perfect cylinders before slicing, as shown. Arrange a layer of potato slices, overlapping them, in concentric circles on the paper. This layer will eventually be the top of the potato cake. Season with salt and pepper and add slices of butter or melt the butter and dribble it over. Arrange a second layer of potatoes on top, season with salt and pepper, and add or sprinkle with butter. Continue to make layers until you have used up all the potatoes and butter. Place a second round of parchment paper, the same size as the first, over the cake. Set a smaller pot or lid over the potatoes to weight them down.
Bake for 25 minutes, or until the cake shrinks slightly and the sides are golden brown.
While holding the potatoes in place with the back of a spatula, pour out the excess butter into a heatproof bowl. Peel off the paper. Place a plate, ideally one that just fits into the pan over the potatoes, on top of the cake. Invert the pan and plate together and lift off the pan. Peel off the paper. Gently slide the potatoes back into the pan and then pour the butter back into the pan.
Return the pan to the oven and bake the potatoes for 15 minutes longer, or until brown on the sides. To serve, pour off the excess butter from the pan and then slide the cake out onto a large plate. Cut into wedges at the table.
Peel large waxy potatoes. Shape the first two potatoes into perfect cylinders.
Brush the bottom of a sauté pan with soft butter. Fold and cut parchment to line pan.
Place the round of parchment in the buttered pan. Brush the parchment with butter.
Using a mandoline, slice 1 shaped potato into rounds the thickness of a quarter.
Arrange the slices, overlapping them, in concentric circles in the pan.
Thinly slice butter and place evenly over the potatoes. Season with salt and pepper.
Slice the remaining shaped potatoes and arrange in layers in the same way, topping each layer with thin butter slices, salt, and pepper. Cover the top with a round of parchment paper.
Place a pan or lid over the potatoes and weight it down with another pan.
Bake at 400° for 25 minutes, remove the weight, and cook for 15 minutes. When the surface of the potatoes is brown around the edges, take off the parchment.
Run a knife around the inside edges of the pan to detach any potatoes that have stuck. Place an ovenproof serving plate over the pan and invert both to dislodge the potatoes from the pan and onto the plate.
Gently peel away the parchment.
Return the potatoes to the oven to brown the top, or invert them into another pan with butter to brown the top on the stove top. Serve cut into wedges.