Ingredients:

  • Confectioners' (powdered) sugar: 4 cups (480 g)
  • Meringue powder: 3 tablespoons (21 g)
  • Warm water: 6–8 tablespoons (90–120 mL), divided
  • Light corn syrup: 2 tablespoons (30 mL)
  • Pure vanilla extract: 1 teaspoon (5 mL)
  • Fine sea salt (optional): a pinch (~1/8 teaspoon / 0.5 g)
  • Gel or paste food coloring (concentrated): amounts as needed
  • Water (for thinning small batches as needed): small spoonfuls
  • Optional: lemon or almond extract in place of vanilla: 1/2–1 teaspoon (2–5 mL)

Instructions:

  1. Prep: Gather ingredients and tools; line a tray with parchment for drying cookies. Sift powdered sugar if lumpy for extra smoothness.
  2. Make the meringue base: Combine meringue powder with 2–3 tablespoons (30–45 mL) warm water in the mixer bowl and whip briefly until foamy. Gradually add about half the powdered sugar and beat to combine.
  3. Build the icing: With mixer on low, add remaining powdered sugar in batches. Add corn syrup, vanilla, a pinch of salt, and remaining water (start with 2 tablespoons; add more to reach desired consistency). Beat until smooth and glossy.
  4. Test and adjust consistency: For outlines use stiffer icing that forms a peak and holds shape. For flooding thin slightly with water until a drizzled ribbon smooths out in about 10–15 seconds. If too thin add powdered sugar; if too stiff add drops of water.
  5. Divide and color: Portion base into small bowls for each color. Add gel or paste coloring a little at a time until desired shade; stir gently to avoid aeration.
  6. Transfer to dispensers: Spoon icing into squeeze bottles or fitted piping bags. Keep unused icing covered with a damp towel or plastic wrap to prevent crusting.
  7. Decorate cookies: Pipe an outline along the cookie edge using stiff icing and let crust slightly (1–5 minutes). Flood the interior with thinner icing from a bottle or bag; use a scribe or toothpick to spread icing evenly and pop air bubbles. Add wet-on-wet details if desired.
  8. Drying and finishing: Let cookies dry undisturbed on a flat surface: most floods are surface-dry in 1–4 hours and fully set in 8–12 hours. Once dry, store in an airtight container separated by parchment layers.
  9. Key visual cues: Piping icing forms a peak that holds and smooths minimally; flooding icing flows and levels within ~10–15 seconds; finished cookies lose tack and feel matte/dry when fully set.