Palmiers (also called palm leaves or pigs' ears) have a shell of caramelized sugar. Once they are in the oven, watch them closely or they may go from a perfect dark golden brown to burnt in seconds.
Sprinkle half the sugar on a clean work surface. Place dough on top, and sprinkle evenly with remaining sugar.
Using a rolling pin, gently roll out dough into a 9 1/2-by-15-inch rectangle 1/8 inch thick, being careful not to press too hard around the edges. Continually coat both sides with sugar.
Place dough so that one of the long sides is closest to you. Using your fingers, roll dough lengthwise into a long cylinder, as tightly as possible without stretching it, as you would a roll of wrapping paper, stopping when you reach the middle. Repeat the same rolling procedure with the other long side until you have two tight cylinders that meet in the middle. Wrap tightly in plastic wrap; place in refrigerator to chill at least 1 hour.
Unwrap dough; using a sharp knife, cut dough crosswise into 3/8-inch-thick slices. Place palmiers on an ungreased baking sheet, and firmly flatten with the palm of your hand. Cover with plastic wrap; place in refrigerator 1 hour.
Preheat oven to 425 degrees. Place palmiers in oven, and bake 5 minutes. Reduce oven temperature to 400 degrees; continue baking until pastry is golden brown and well caramelized, about 10 minutes. Remove from oven; using a thin spatula, immediately transfer palmiers to a wire rack to cool completely. Serve shiny side up.