For the biscuits: heat the oven to 190°C (170° fan) 375°F gas 5. Line a large baking tray with non-stick baking paper.
Beat the butter and sugar together in a bowl until soft and light.
Beat in the egg and lemon zest, a little at a time, until blended.
Stir in the flour and mix to a dough.
Roll out the dough out on a lightly floured surface to a thickness of 1cm|1/2". Using a cookie cutter or card template, cut ghost shapes out of the dough and place on the baking tray.
Bake for 8-10 minutes until cooked through. Cool on the baking tray for 5 minutes, then place on a wire rack to cool completely.
To decorate: sift the icing sugar into a bowl and beat in the lemon juice. Add just enough water to give a thick consistency- the mixture should be thick enough to coat the back of a spoon.
Spread a thick layer of icing over the biscuits. Shape small rings from the sugarpaste and attach to the biscuits for the eyes. Place half a jellybean in each ring for the eyeballs and attach a whole jellybean for the mouth. Leave to set.