Here is the recipe I am talking about
Antonia74 Royal Icing
Serves/Yields: about 6 cups of thick icing?
Prep. Time: 12 minutes
Cook Time:
Category: Frostings, Cookies!
Difficulty: Easy
This icing is mixed to a stiff consistency for outlining cookies, then can be thinned with warm water to fill in the cookie shape. I like to dry my cookies for at least 24 hours...and up to 48 hours before packaging them. This icing can be kept at room temperature in an air-sealed container for literally weeks, with a good re-mixing before you use it again. I haven't had great results with keeping it in the fridge...but un-tinted icing (i.e. white) seems to be okay from the freezer.
6 oz (3/4 cup) of warm water
5 Tablespoons meringue powder
1 teaspoon cream of tartar
1 kilogram (2.25 lbs.) powdered icing sugar
In mixer bowl, pour in the warm water and the meringue powder. Mix it with a whisk by hand until it is frothy and thickened...about 30 seconds.
Add the cream of tartar and mix for 30 seconds more.
Pour in all the icing sugar at once and place the bowl on the mixer.
Using the paddle attachment on the LOWEST speed, mix slowly for a full 10 minutes. Icing will get thick and creamy.
Cover the bowl with a dampened tea-towel to prevent crusting and drying.
Tint with food colourings or thin the icing with small amounts of warm water to reach the desired consistency