Sift the powdered sugar. Measure 2 cups powdered sugar and sift it into a medium bowl. This removes lumps and gives a smooth finish.

Add the wet ingredients. Stir in 2 to 3 tablespoons milk (or water), 1 tablespoon light corn syrup, 1 teaspoon vanilla extract, and a tiny pinch of salt.

Mix until glossy. Whisk until the icing is smooth and shiny. It should slowly ribbon off the whisk. If it’s too thick, add milk 1/2 teaspoon at a time. If too thin, add a bit more powdered sugar.

Adjust consistency for your task. For piping outlines and details, aim for a toothpaste-like thickness. For flooding, thin to a honey-like pour that settles in 10–15 seconds when you drizzle some across the surface.

Color as desired. Divide into bowls and add gel food coloring. Mix gently to avoid bubbles. Cover each bowl with plastic wrap touching the surface so it doesn’t crust over.

Pipe the outline. Transfer piping-consistency icing to a piping bag fitted with a small round tip (or use a zip-top bag with a tiny snip). Outline each cookie and let it set for 5–10 minutes.

Flood the cookie. Thin icing slightly for flooding. Fill the inside of the outline, then use a toothpick or scribe tool to nudge icing to the edges and pop bubbles.

Add details. Let the base dry 20–30 minutes before adding details on top so they don’t sink. For crisp layered designs, wait 1–2 hours.

Dry completely. Let cookies dry at room temperature until fully set, usually 8–12 hours or overnight. Avoid humidity and cover lightly with a clean box or tent to protect from dust.

Store or serve. Once hardened, stack, pack, or gift without smearing.