Preheat your oven to 200ºc/180ºc Fan and line 3-4 baking trays with parchment paper.
Cream together the unsalted butter and caster sugar until light & fluffy, then gradually beat in the egg and vanilla bean extract so that the mixture is smooth.
Add in the Plain Flour and beat again till the dough is combined.
Roll the mixture out on a lightly floured work surface to the thickness of two £1 coins.
Cut them out in the various shapes that you want - I used 6cm size cutters but in various different shapes so that I had a mixture!
Place them onto the lined baking trays a couple of centimetres apart and bake in the oven for 8-10 minutes until they start to go golden around the edges.
Leave to cool on a wire rack.
Decoration
Loosen a few spoonfuls of the royal icing with a few drops of water (just a little so that when you leave a trail of icing going through itself, it stays there for about 20-30 seconds).
Pipe this round the edge of the cookies, or in whatever pattern you please!
Once they're all done, leave the icing to harden slightly for about 15 minutes.
Once the icing has hardened, split the rest of the icing off into the colours you want to use and loosen the icing again, this time adding slightly more water so that the trail lasts about 5-8 seconds.
Fill all of the gaps with the icing so that you're doing "run outs" of icing and then leave to dry.
Add any more decoration that you please - I painted on some darker colours to give the cookies slightly more depth simply using water downed paste food colourings! Enjoy!
Notes
I used the Renshaw Ready To Use Royal Icing as I was sent the product to review - and honestly it is so much easier than making it yourself, and it's the perfect amount in the tub! If you want your cookies to have a little more depth, you can add a layer of fondant to the cookies, then decorate with the Royal Icing!
These will last 4-5 days in an airtight container, or you can freeze them for up to 3 months.