1. Combine confectioners sugar and meringue powder with a whisk.
2. Add 6 Tbsp. water. Beat on low until combined, then medium to high 5-6 minutes. At this time you can divide the icing and stir in coloring by hand.
3. The icing should be a consistency* that would allow it to keep its shape when piped. For each color, fill a pastry bag, decorator, or plastic zipper baggie (snip small opening in corner) with ½ of the icing. This will be the outline icing. The icing remaining in the bowls will become the background icing and will need to have water added, ½ tsp. at a time, until it is the consistency* of heavy cream.
4. Outline the cookie using the outline icing in the pastry bag. Next, fill in the entire cookie with the background icing using a teaspoon or small 6 oz. plastic squeeze bottle. Use a small toothpick or popsicle stick to push frosting into corners. The outline should blend.
5. Once the cookie is covered with a layer of frosting, allow to dry until set before adding additional frosting. For additional detailing use the thicker outline frosting. Sprinkles may be added after a few minutes.
6. Use icing immediately, covering bowl with damp paper towel or plastic wrap while in use. Store in an airtight container.
*If icing is too thin, add more confectioners sugar. If icing is too thick, add more water.