Heat the oven to Gas Mk 2, 150°C. Beat the eggs whites with a pinch of salt until they form soft peaks, then gradually trickle in the sugar and vanilla sugar and continue beating until the mixture is firm and glossy. Transfer to a piping bag with a large plain nozzle.
Pipe 16-20 ghosts onto a baking tray lined with baking parchment and dry in a preheated oven (100°C) for about 2 hours, leaving the oven door open a crack. The meringues should not brown. If necessary, reduce the oven temperature to 80°C and dry for a little longer.
Melt the chocolate over a bain-marie and put into a freezer bag. Cut off a corner to make a tiny hole and pipe two eyes on each ghost.
Leave to dry before serving.
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