Add the powdered sugar to a large mixing bowl attached to your stand mixer, as well as the meringue powder and stir a little to mix.
Using your wire whip, turn on your stand mixer on a low speed and slowly add the water. As the powder subsides you can turn up the speed to medium.
Whip the mixture well for about 7-10 minutes, until you start to see tips forming.
Check the consistency of the icing. If it falls off the wire whip and melts back into the bowl of icing within 5-10 seconds then it’s perfect.
Cover the bowl tightly with plastic wrap until you are ready to use it.
Take a piping bag and a number three tip and place into a tall glass, folding the edges over the outside of the glass. This is the easiest way to fill up an icing bag with less mess.
Use a rubber band to tie the top of the icing bag. Place a piece of wet paper towel in the bottom of the glass, this will help the tip stay moist while you are working.
If you are using other colors, pour a little of the remaining icing into a small bowl and mix in a little of the food color until you reach the desired color.
If your cookies have a white background, which most of mine did (in the images), use the piping bag to pipe the icing around the outside edges, and then fill the middle. Use a toothpick to spread the icing evenly.
Leave cookie to set while you move onto the next, or if you are using sprinkles on your cookies sprinkle them on at this point, while the icing is still wet.
Use the colors you have mixed and a toothpick to create the designs on the cookies. If you are putting a design on the white background let the white set first before you start with your next color.