Cream the butter and Caster sugar together. Beat in the egg and vanilla until well combined.
Sieve the flour and add to the mixture. Flatten slightly and wrap in cling film. Place in the fridge for 30 minutes. Sprinkle a little flour on to a work surface, roll out the cookie dough to an even thickness (approx 1/2 inch). Cut out shapes with a cookie cutter. Carefully put them on a lined baking tray and return to the fridge for another 30 minutes.
Bake at 150℃ for 20-25 minutes until the cookies are golden brown.
Allow to cool on tray for 10 minutes then transfer onto a wire rack.
Allow to cool completely.
To decorate the cookies with Siúcra Instant Royal Icing Sieve the Siucra Royal Icing Sugar into a bowl and follow the directions on the packet to make it. Divide between two bowls. Colour one bowl with pink food colouring and the other with purple. Fill a small piping bag with one of the coloured icings. Pipe around the edge of the cookie. Carefully fill the middle of the cookie with the other coloured icing.
To decorate the cookies with Siúcra Roll Out Icing Dust a work surface with Siúcra icing sugar. Lightly knead the Siúcra Roll Out Icing sugar for 2 minutes. Sprinkle a little Siúcra Icing sugar on a work surface and roll out the icing to 1/2 inch thick. Use the same shape cookie cutter as used for the cookies and cut out the icing. Spread a thin layer of Siúcra Instant Royal Icing onto the cookies then stick the roll out icing on top. The Siúcra Siúcra Roll Out Icing can also be coloured with food colouring.