Royal icing is perfect for detailed decorations and fun cookies. It is simple to make and versatile. I am also sharing my favorite shortcut method for using it to decorate cookies quickly!
Start by emptying the powdered sugar into your mixer bowl with the whisk attached. Add the meringue powder and put on low for a couple of seconds to mix it.
Warm up about a 1/4 cup of water and add the flavoring (and corn syrup if using). While the mixer is on low, slowly pour it in. Get a little more warm water in your measuring cup.
Slowly drizzle in a little bit of water at a time until you reach the consistency of honey.
Then turn the mixer up to medium-high for a few minutes. The mixture should get glossy and airy. It is done when it can hold a stiff peak.
At this point, you can scoop the icing into air tight containers and keep on the counter for up to a couple of weeks. I usually put it into a variety of smaller containers, so there isn't much air between the icing and the lid and so I don't have to keep getting icing from the same big container. I am not sure if this matters at all, but it is what I normally do.
When you are ready to use the frosting, scoop what you need into a glass measuring cup and color. It is best to do all of what you need for a certain color at one time so that it is consistent, it will be nearly impossible to match the color later. If you want to outline and flood, you'll want to adjust the whole thing (by adding a drop of water at a time) to your outline consistency. Take out what you want for outlining, then continue to thin what is left until you have your desired flood consistency. Be sure to add slowly, it's hard to fix if you've added to much.
Repeat step six for all of your colors and go to work frosting!
Notes
*Make sure your flavorings don't contain oil. We usually use a mix of vanilla and lemon or almond.Some people swear by adding corn syrup. I have done it both ways and don't see much of a difference. So whether or not I add it to a batch mostly has to do with if I have some on hand and if I think of it.