Royal Icing Recipe
2 lbs powdered sugar
3 tablespoons meringue powder
2 tablespoons corn syrup
3/4 cup water
In a bowl used with an electric mixer (I use a Kitchen Aid mixer), add the meringue powder and water, whisk together until it foams. Add the powdered sugar and corn syrup. Start slow and mix everything together. Once mixed together, mix on high for 3 min.
Separate out and add food coloring. Add water 1 tsp at a time to get the consistency you desire (this take LOTS of practice and trial and error).
See my 'favorite things' post for the equipment I use.