Q: When I make royal icing, either the texture is off or the color isn't uniform. Do you have any tips?
A: Royal icing, made primarily of sifted confectioners' sugar and egg whites or meringue powder, dries hard with a glossy sheen, making it ideal for decorating cutout cookies.
Success in working with royal icing depends on a careful hand. When mixing, use the paddle attachment on low speed, and stop once ingredients are fully incorporated. It's essential not to over-beat: Doing so produces a foamy texture that turns brittle and dull when it dries.
Over-beaten icing may also cause blooming -- once it sets on the cookie, its color might look patchy. Although this doesn't affect flavor, it can mar the prettiness of an otherwise perfect confection. Unfortunately, there's no good way to salvage royal icing that has been over-beaten. If you've already decorated a cookie, in a pinch you can use a damp pastry brush on the bloomed area and sprinkle it with sanding sugar.
To achieve icing with the right consistency, check its texture intermittently while you're beating. Fine-tune it by adding small amounts of water or sifted sugar. The decorating technique you'll use plays a role in how dense the mixture should be. To "flood" cookies -- cover the entire surface -- make icing that's fairly thick but loose, about the consistency of honey. You can thin the mixture by adding water one teaspoon at a time. For piping and detail work, the icing should be stiff enough to hold its shape; add more sifted confectioners' sugar, a little at a time, until the icing has the thickness and body you desire.
Use color sparingly, because the hue will deepen once the icing dries. Gel-paste colors (sugarcraft.com) are preferable to liquid food colorings. They are more intense, so you need less, which means you won't change the consistency of your icing. If you're not using the icing immediately, cover the bowl with a damp dish towel and plastic wrap to keep it from drying out.
You can try these tips by creating colorful holiday cookies or building a peppermint house.