Royal Icing for Piping and Flooding

Before you start

Royal icing is powdered sugar beaten with egg white protein and water until it forms a bright white, glossy paste. It dries hard and matte, which is why it is used for decorated sugar cookies, gingerbread houses and piped details that need to hold their shape. Meringue powder, a dried and pasteurized egg white product, makes it consistent and avoids the questions that come with raw whites.

The skill is consistency. You mix one stiff batch, then thin portions with water a few drops at a time. Stiff icing pipes flowers and glues gingerbread walls; a medium outline icing pipes a clean border that does not spread; flood icing is thin enough to settle into a smooth, flat surface. Decorators often describe these by how many seconds a line drawn through the surface takes to disappear, which is the simplest way to judge them at home.

Ingredients

• 480 g (4 cups) powdered sugar — sifted
• 3 tbsp (about 30 g) meringue powder
• 90–120 ml (6–8 tbsp) warm water — plus more for thinning
• ½ tsp clear vanilla extract or lemon juice

Method

1. Whisk the sifted powdered sugar and meringue powder in the mixer bowl. Make sure the bowl and paddle are free of grease, which weakens the icing.
2. Add 90 ml (6 tbsp) warm water and the vanilla or lemon. Mix on low until combined, then beat on medium for 4 to 5 minutes, until the icing is thick, glossy and holds a stiff peak that does not bend. This is stiff consistency.
3. If the icing is too stiff to beat, add more water 1 tsp at a time. Keep the bowl covered with a damp cloth whenever you are not using it, because royal icing crusts within minutes.
4. Divide the icing into bowls and tint each with gel color. Mix gently with a spatula rather than a whisk to avoid adding air bubbles.
5. For outline icing, add water a few drops at a time until a line cut through the surface with a knife closes in 15 to 20 seconds. It should pipe a smooth line that holds its edge.
6. For flood icing, keep thinning until the line closes in about 10 to 12 seconds. Cover the bowl and let it sit for 5 minutes, then stir gently to pop rising bubbles.
7. Outline a cookie, let the border set for a few minutes, then fill the center with flood icing and nudge it into the corners with a scribe or toothpick. Let the cookies dry uncovered at room temperature.

Tips for success

• Colors deepen as the icing dries, especially reds and blacks. Mix them a few hours ahead if you can and judge the color after resting.
• A small fan blowing gently across freshly flooded cookies helps the surface dry faster and shinier.
• For wet-on-wet designs such as dots and marbling, pipe the second color onto the flood layer immediately, before it begins to crust.

Substitutions

Meringue powder

Use 2 large pasteurized egg whites, about 70 g, in place of the meringue powder and most of the water. Raw unpasteurized whites are not recommended for icing that will not be cooked.

Clear vanilla

Regular vanilla extract adds a faint ivory tint. Almond extract (use ¼ tsp) gives a classic bakery flavor.

Water

Strained lemon juice for some of the water gives a brighter flavor and a slightly harder set.

Variations

Gingerbread house cement

Use the icing at stiff consistency with no extra water and add 1 tbsp more meringue powder for extra holding power.

Lemon glaze icing

Thin a portion with lemon juice to flood consistency for a tart, glossy finish on shortbread.

Troubleshooting

Flood icing has craters or sinkholes

Air bubbles or icing that was too thin. Let the thinned icing rest, pop bubbles with a scribe, and thicken it slightly with stiff icing.

Icing never dries hard

It was overthinned, there was grease in the bowl, or the room is humid. Thicken it with more stiff icing and dry cookies in a cool, dry room or near a fan.

Colors bled into each other

The base layer was not dry enough or the icing was too thin. Let each section crust for 30 to 60 minutes before piping a neighboring color.

Storage

Press plastic wrap onto the surface and keep the icing in an airtight container at cool room temperature for up to 3 days, or refrigerate for up to 1 week. It separates as it stands; re-beat before using. Decorated, fully dry cookies keep airtight for about a week.

Safety notes

Meringue powder is a pasteurized egg product. If you use fresh whites instead, choose pasteurized eggs, since royal icing is never cooked. Contains egg.