Step 1

Combine the powdered sugar, 2 tablespoons (30 ml) of milk, light corn syrup, and vanilla extract in a large mixing bowl and whisk until well combined and no lumps remain. The mixture will be pretty thick at this point.

Step 2

Add 1/2 teaspoon of milk (5 ml) at a time until the icing has thinned out and reached an outline consistency. To test the icing, lift the whisk or spoon from the mixing bowl, you should still see the ribbons of icing that fall back into the bowl for 3-4 seconds. If needed, add more milk to thin out the icing or add more powdered sugar to make it thicker.

Step 3

Add the gel food coloring and mix until fully combined. Remove 1/3 of the mixture for the outline icing and set aside.

Step 4

Add 1/2 teaspoon of milk (5 ml) at a time to the remaining 2/3 of the mixture until the icing reaches a filling consistency. When you lift your whisk or spoon from the bowl, the icing should quickly melt back into the bowl of icing.

Step 5

Place the outline icing and fill icing in separate piping bags (or zip lock bags) and cut the tip off of each one. Outline each cookie with the outline icing, then use the fill icing to fill in the cookie. Use a toothpick if needed to move the icing around and fill in any empty spots.

Step 6

Place the cookies in a single layer in an airtight container and allow the icing to fully harden for about 24 hours.