Recipe from Love To Know - Vegetarian.
No-Egg Royal Icing
4 1/2 cups confectioner's sugar
1 Tbs. cornstarch
1/2 teaspoon xanthan gum
1/3 cup water
1/2 teaspoon clear vanilla extract
In a glass bowl, whisk together the sugar, cornstarch and xanthan gum.
Using an electric mixer set on low speed, slowly add the water.
Add the extract and continue mixing until the icing is smooth and thick enough to pull up peaks.