Royal Icing Christmas Cookies

Count it. Drag a knife through the bowl and time how long the line takes to disappear. Fifteen to twenty seconds is outline consistency, stiff enough to hold a border. Ten to twelve seconds floods a cookie and settles smooth on its own. Thin with water half a teaspoon at a time, because thinning icing is easy and thickening it means more sugar and a second mix.

Start with a powder that is white on its own. Meringue Powder whips a bright white icing with no titanium dioxide in it, so there is nothing to tint back. Use clear vanilla, since a brown extract pulls the icing toward cream, and dry the cookies away from the oven and out of sunlight, because warmth lets butter from the cookie seep up and stain a white coat.

Either makes royal icing, and meringue powder is the one most decorators reach for. Raw egg whites carry a food-safety risk on cookies that sit out for days, and the amount in a batch changes with the egg. Meringue Powder measures the same every time and whips a glossy icing that pipes cleanly and dries hard enough to stack.

A flood coat is dry to the touch in about an hour and set through in six to eight, longer on a humid day. Give decorated cookies a full night uncovered before stacking, bagging or boxing, and a small fan pointed at the tray cuts that time in half. For shipping, dry them a second day, then pack in single layers with parchment between and no room to slide.

Use gel color, not liquid, and mix the red a day ahead so it deepens on its own without extra dye. Let each flooded color crust for at least an hour before piping the next one against it, and dry the tray with a fan nearby. Or skip tinted icing altogether: pipe white, press Naturally-Colored Sanding Sugar in red or green onto the wet icing, and the color sits on top where it stays put.

Press plastic wrap onto the surface so it never meets air, then lid the container. It keeps about two weeks at room temperature or a month in the fridge. Water separates out as it sits, so stir it back in and give it a few seconds with the mixer before piping. Icing left in a bag on the counter skins over and clogs the tip, so refill from the covered bowl instead.