In a medium bowl, combine confectioners' sugar, vanilla extract, corn syrup, and 4 tablespoons of water. Begin stirring with a fork until the mixture starts to come together.

Switch to a whisk and add the remaining water, 1/2 tablespoon at a time, until the frosting reaches a consistency where it drizzles smoothly from the whisk but still holds shape for a few seconds.

If using food coloring, add a drop or two to the frosting and stir well. Add more coloring as needed to achieve the desired hue.

Transfer the frosting to squeeze bottles or piping bags fitted with a small round tip. Outline the gingerbread cookies with frosting first, then fill in the centers.

Allow the frosting to dry completely, which may take up to 24 hours, before storing or serving the cookies.