These tie-dye heart cookies are decorated with a super easy dip-and-swirl royal icing technique that creates a marbled, colorful finish on every cookie. No piping required, and each cookie turns out a little different.
Add water one drop at a time, stirring well after each addition, until the icing is slightly thinner than piping consistency and will easily flood the cookie
Pour icing into a bowl
Transfer the thinned icing to a shallow bowl, about the size of a cereal bowl
Add color swirls
Dip the tip of a butter knife into gel food coloring, then gently swirl the knife through the icing to create ribbons of color. Avoid overmixing
Dip the cookie
Hold a cooled heart-shaped cookie by the edges and slowly lower it face-down into the icing
Twist and coat
Give the cookie a gentle twist and slight dunk to ensure the entire surface is coated
Lift and drip
Lift the cookie and allow most of the excess icing to drip back into the bowl
Flip and set
Quickly flip the cookie icing-side up and place it on a baker’s cooling rack to harden, place a piece of parchment paper under the wire rack to catch the icing that drips off
Repeat
Repeat with remaining cookies, adding additional color swirls as needed to maintain the tie-dye effect