Heat your oven to 180⁰C/350⁰F/gas mark 4 and lightly grease two baking trays.
Cream the caster sugar and butter together until nice and fluffy. Add the eggs and vanilla and mix briefly.
Sift the flour, baking powder and salt together.
Next the dry ingredients to the butter and eggs and mix gently. The mixture will form a dough.
If it is too sticky, add a little more flour (be sparing).
Bring the dough together into a disk, wrap in cling film and rest in the fridge for 1 hour.
Roll out the dough to approximately a half of a centimetre thick.
Using floured Halloween shaped cookie cutters, cut the biscuits out and place on the baking tray. Collect up the trimmings and re-roll to cut out as many biscuits as you can.
Bake for between 8 and 10 minutes in the preheated oven until golden.
Remove from the oven and cool on wire racks.
To make the glace icing:
Put the icing sugar into a bowl and add 2 tablespoons of warm water and mix well. You may need to add a little more water to make a slighly dropping consistency - if it's too runny and thin, just add a little more icing sugar.
Divide the icing into 3 bowls and colour with halloween colours such as orange, green and black.
Ice and decorate.