This simple recipe for royal icing is perfect for decorating all kinds of cookies!
Combine meringue powder and warm water until dissolved. Beat for about 1 minute. Add powdered sugar and corn syrup. Mix at medium speed for about five minutes. Remove a small amount of royal icing to a small bowl and add a little bit of water - drop by drop - until it's the consistency you want. Don't try to get all the royal icing to the same consistency at the same time.
If you are planning on piping some designs on your cookies, you will want your royal icing to be a little bit thick. After you pipe your designs, you can thin out your royal icing a little bit more so you can flood your designs to fill in the empty spaces. It's up to you! We mainly just piped designs on our gingerbread men and did very little flooding. Make sure that any royal icing that you are not using stays covered! It will dry out quickly! Store extra royal icing with a layer of plastic wrap touching the icing and then cover the entire container. Store in the fridge.