Difficulty: Medium
Preheat the oven to 210°C (th. 7).
Unroll the puff pastry squares and cut 9 in half lengthwise, reserving the rest. This yields 18 rectangles (7 cm x 14 cm). Prick with a fork, brush with egg yolk, dust with icing sugar, and bake for 5 minutes. Flatten with a saucepan base, then bake until golden.
Meanwhile, whip very cold cream with vanilla sugar into firm peaks.
Cool the pastry rectangles completely.
Pipe cream onto 6 rectangles. Dust with cocoa, add broken chestnuts, top with another rectangle, and repeat. Finish with the last layer.
Garnish with cream rosettes and candied cherries. Serve immediately.
