The easiest way to add gold is to make a paint by mixing a bit of edible gold luster dust with a few drops of volka. Then all you have to do is paint it onto completely dry royal icing.
From experience, I've learned that it pays to buy good quality luster dusts. Inexpensive ones don't dissolve very well and tend to look grainy and clumpy on the cookies. I think Crystal Colors makes the best ones and they can be purchased online. I ordered the Gold Blush color I used for these from Global Sugar Art.
|My favorite luster dust.|
|Painting the gold onto a brushed embroidery cookie. It's important that the royal icing be completely dry before you add the gold.|