Place the marzipan into a food processor or blender with about half of the sugar and process until well blended. Add the butter and remaining sugar and process until smooth, then blend in 1 egg, vanilla essence, almond essence, flour and salt. Set aside.
Preheat the oven to 220 degrees C. Butter a baking tray or line with baking paper and set aside.
Roll out one sheet of the puff pastry into a 30cm square. Keep the pastry cool, do not knead or stretch. Use a large pie plate, cake pan or frying pan to trace an circle onto the dough using the tip of a small knife. Place the circle of pastry onto the prepared baking tray. Repeat with the second sheet of pastry. Refrigerate both sheets.
Mound the marzipan filling onto the centre of on sheet of the pastry that is on the baking tray. Leave about a 4cm margin at the edges. Press the bean down somewhere into the filling. Place the second sheet of pastry on top and press down the edges to seal.
Beat the remaining egg with a fork and lightly brush onto the top of the cake. Use a knife to make a criss cross pattern in the egg wash and then prick several small slits in the top to vent steam while baking.
Bake for 15 minutes in the preheated oven. Do not open the oven until the time is up, as the pastry will not fully puff. Remove from the oven and dust with icing sugar. Return to the oven and cook for an additional 12 to 15 minutes or until the top is a deep golden brown. Transfer to a wire rack to cool.
Lay a paper crown gently on top of the cake. This will be used to crown the person who finds the bean. Serve warm or cold.