Make cookies one day in advance. Prepare and roll out cookie dough following recipe directions. Use egg cookie cutter from set to cut out cookies. Bake and cool cookies.
Prepare Color Flow icing following recipe directions. Tint large portion sky blue and small portion brown.
Use tip 3, cut disposable decorating bag and full-strength sky blue icing to pipe outline of egg. Use thinned sky blue icing in cut disposable decorating bag to flow in. Immediately use thinned brown icing in cut disposable decorating bag to pipe various size spots. Use a toothpick to drag and swirl designs as desired. Let dry 24 hours.
Thin brown icing to very watery consistency. Dip decorator brush in very thin brown icing and flick it over cookies to add speckled splatters. Let dry 2 to 4 hours.