In a medium bowl mix together the flour, baking powder and salt. Set aside
In a bowl of an electric mixer, beat he butter on a medium-high speed until pale and fluffy, about 2 minutes. Add sugar and and beat until creamed (for about 2 more minutes). Add the egg and vanilla and and beat on high speed until well combined. Make sure to scrape the sides and the bottom of the bowl to make sure it all gets combined together.
Add the flour mix into the butter mixture and mix on low speed until combined. If the dough feels to sticky to roll, add 1 tbsp of flour to it (or more, until it's texture is good enough for rolling).
Divide the dough into two equal parts and roll each part on a lightly floured baking paper to about £1 coin thickness. Transfer the rolled dough into the fridge (if stacking one on top of each other, make sure to cover the top one with some baking paper too, so it doesn't dry out). Chill for at least 1-2 hours or overnight.
Once chilled, preheat the oven to 170 C (fan). Line t baking trays with some baking paper. Remove one of he pre-rolled dough pieces from the fridge. Using your favourite cookie cutters, ct the desired shapes. Re-roll any remaining dough and repeat until you have used all of the dough. Do the same with the second piece of chilled dough.
Transfer the cookies onto baking tray and bake in the middle shelf of the oven for about 10 minutes, rotating the tray half way through. They are ready when the edges are turning lightly brown. Take out of the oven, and allow them to cool for about 5 minutes, then transfer to a cooling rack to cool completely.
For the icing:
In a bowl of a standing mixer fitted with whisk attachment or hand-held electric mixer with beaters, place all of the icing ingredients and mix together for about 2 minutes until well combined. When lifting the whisk up of the icing, the icing should drizzle down and smooth out within 10- 12 seconds ('draw' a line with the dripping icing, if it disappears after 10-12 seconds and melts back into the rest of the icing, you are good to go).
If the icing is too thick, add a bit more water, a little at a time. If the icing is too thin, add a little more sifted icing sugar.
If using gel food colouring, divide the icing into separate bowls. Add few drops of gel food colouring at a time to each bowl and mix until you reach the desired colour. Make sure to keep checking the consistency of the icing, as gel food colouring may change it and icing can become too thin.
Transfer the royal icing into piping bags and snip the very tip of each piping bag. Decorate the cookies with icing as you desire.
This recipe makes a big batch of cookies, but the exact amount will depend on the type and size of your cookie cutters.
You can fit piping bags with very thin, round nozzles to decorate the cookies, but it is not necessary.
If not nozzles, snip each piping bag at a very tip of it. You want a very tiny opening that will create thin flow.
Allow the cookies to cool down completely before decorating.
Allow the icing to dry before adding any more detail made out of icing again.