To make the base, cream the butter and sugar together, add the egg and mix well to incorporate.
Add the vanilla extract and sugar, and knead to form a dough.
Cover the dough in clingfilm, and refrigerate for 30 minutes.
Use a rolling pin to roll the dough, and use a round cookie cutter or a glass to cut out rounds - I cut out 15, but you can get more or less depending on the size of the cutter.
Arrange the circles on a baking tray lined with non-stick paper and refrigerate again for 10 minutes.
Preheat the oven to 180 degrees Celsius (350 Fahrenheit).
Bake the cookies for 12 minutes until the edges are slightly light brown and still a bit soft.
Leave to cool completely to firm up.
To make the sugar paste, sift the icing sugar, add the milk and vanilla extract, and mix to get a smooth paste.
Divide it between 2 bowls, one will stay white, the other half will have the red food colouring added to it to create a red paste.
Add the white paste to a piping bag, and decorate each cookie, then use a teaspoon to splatter the red paste over.