Here is my recipe for icing for my cookies!
2lbs powdered sugar
1 tbsp meringue powder (Wilton brand)
2 tbsp corn syrup
1/4 to 1/2 cup water
Combine powdered sugar and meringue powder in a bowl. Add half of the water while mixing with an electric mixer. Add the corn syrup while mixing. Add the rest of the water slowly, until the mixture flows like elmer's glue. You may need to add more or less water. It is not an exact science. Mix the icing for at least 5 minutes.
I ice my cookies with pastry bags and cake decorating tips. I flood and fill my cookies with the same consitency. If you want to add flowers to the tops of cookies, you would use plain royal icing from Wilton's recipe.