3 ounces (6 tablespoons or 3 large) pasteurized egg whites
1 teaspoon vanilla extract, or another flavored extract
4 cups (460g or 1 pound) powdered sugar
Use a stand mixer with a whisk attachment, combine egg whites and vanilla until frothy (15-20 seconds).
Sift 1 cup of powdered sugar over the mixture, mix on medium speed until absorbed, scraping down sides if needed.
Lift the whisk and observe how long it takes for the icing thread to disappear (aim for 8-10 seconds); adjust thickness by adding sifted powdered sugar as needed.
Divide into bowls, add food coloring to each; adjust thickness with more powdered sugar for piping or water for flooding.
Transfer piping frosting to a bag with a #3 tip or smaller; pipe outlines or decorations. Use flooding icing to fill spaces if desired.
Let icing dry completely, at least 2 hours with a gentle fan or overnight. Store in an airtight container between parchment for up to 5 days.