Preheat the oven to 180° C
Cream the sugar and butter until the butter is a very pale shade of yellow.
Add the egg and vanilla and keep creaming till light and fluffy.
Mix in the flour with a wooden spoon.
Roll the dough in a ball and cover with plastic.
Rest the dough in the refrigerator for 1 hour
After an hour remove the dough from the refrigerator and roll out on a surface that has been dusted with flour. The dough should be about 8mm thick after rolling out.
Cut out animal shapes with a cookie cutter and place on the baking sheet.
Bake for 10 minutes or until golden in color.
Allow biscuits to cool on the baking sheet.
When cooled down, add all the ingredients for the icing to a small mixing bowl and whisk together.
Place the biscuits on a wired rack on top of a baking sheet and drizzle the icing over. Decorate with silver or colored balls.