Using an electric mixer or a freestanding mixer with paddle attachment, cream the butter for 3-4 minutes until pale and fluffy. Add the sugar and beat again for a couple of minutes to combine.
Add an egg and vanilla and mix to combine.
Tip in the flour and the baking powder and mix to combine.
Divide the dough into two parts. Place one half into a lightly floured baking mat or a sheet of baking paper and roll it into roughly about 5mm thickness. Do the same with the other half, then transfer the rolled dough into the fridge for at least an hour.
Preheat the oven to 180 C (160 C fan).
Remove the dough from the fridge and use your favourite cookie cutters to cut the dough into the desired shape. Re-roll any leftover dough and repeat.
Place the cookies into baking sheets or trays and bake for 10 minutes, or until the edges are just starting to brown. Remove from the oven and allow them to cool completely before decorating with icing.
To make the royal icing, place the royal icing sugar in a bowl of an electric mixer and add the water. Mix to combine for about 2 minutes, until well combined. When lifting the beaters or the whisk from the icing, the icing should drizzle down and smooth out within 10-12 seconds. If it’s too thick, add more water (only a little at a time). If the icing feels too thin, add more sugar to it.
Divide the icing between separate bowls and add food colouring gels into them to create the desired colours. Transfer each colour into separate piping bag.
To decorate, start with drawing a border line around each cookie with the icing, and allow it to dry before flooding the cookie with more icing. Allow the icing to dry completely. Enjoy!
Rolling the cookie dough directly onto the baking mat or baking paper will help you transfer the cookies easily onto the baking trays.
If the dough feels too sticky to roll, place it in the fridge for 20 minutes. You can also try rolling the dough between two sheets of baking paper to stop it from sticking.