Stir together marzipan and light butter. Stir in egg, powdered sugar, vanilla sugar, orange zest, flour and cornstarch. Pour the batter into a piping bag fitted with a smooth nozzle. Line a baking tray with parchment paper. Pipe two strips of about 5 cm each directly (!) on top of each other and a third on top.
Bake in a heated oven (electric oven: 175-200 °C,
gas stove: level 2-3).
Prepare a glaze from powdered sugar, cocoa and orange juice, fill into a parchment bag and squirt in a zigzag pattern over the cookies.