Defrost puff pastry. Using a cookie cutter, cut into circles 6 cm in diameter. Roll each circle into a strip 12 cm long. Lubricate each strip with yolk on top and sprinkle with sugar. Transfer to a baking sheet covered with parchment and bake in an oven preheated to 200 degrees.
Cut the finished strips lengthwise into 2 parts. If the strips did not rise well, then use 2 strips (not cut) for 1 cake. Cool the cream and beat with sugar. On one part of the strip, spread whipped cream in a thick layer and close the top with the sugar part of the strip.