01 - In a medium bowl, whisk together powdered sugar, 2 tablespoons milk, corn syrup, and vanilla extract until smooth and glossy.
02 - If icing is too thick, add additional milk 1/2 teaspoon at a time until reaching thick but pourable consistency.
03 - Divide icing into separate bowls for multiple colors. Stir in food coloring a few drops at a time until desired shade is achieved.
04 - Immediately decorate cooled sugar cookies by dipping, spreading with a knife, or piping designs using a piping bag or squeeze bottle.
05 - Allow decorated cookies to dry at room temperature for at least 4 hours or until icing is completely set.