Mix all ingredients (powdered sugar, vanilla, and milk) to form a thick but flowy paste. Do not make it too runny else it won't stay on the cookies.
To make the colored frosting, divide the white frosting into the number of colors needed and the quantity as needed and add a drop or two of gel food color.
Keep the frosting covered at all times as it dries really fast and will form a layer.
There are three easy ways to frost your cookies
Method 1 - Dip the top of the cookie and let the excess drip off.
Method 2 - Use a spoon to spread the frosting on the cookie (step 23)
Method 3 - Transfer the frosting to a ziplock bag or piping bag. Cut a very small tip and use that to frost your cookies
Get rid of any air bubbles in the frosting by using a toothpick to burst them. You can also use the toothpick to fill small gaps in the frosting by moving it in a circular motion. (See the video, Christmas tree frosting part)
To further decorate, add sprinkles while the frosting is still wet and allow to cool. Or to frost with another color, allow the frosting to set before decorating the cookies with another icing color on top. That way the colors don't mix.
Delicious eggless sugar cookies are ready. Let them air-dry until the frosting is completely set (dry). Store in an airtight container with parchment paper in between each cookie. Baked cookies will stay at room temperature for up to 2 weeks.