Prepare dough and frosting according to the recipes. Before chilling cookie dough, knead a few drops of green food coloring into dough. Chill, cut out and bake star cookies according to the recipe.
Each tree will need 5-6 stars in at least 3 different sizes (you may use more than one of the same size for each tree).
Follow the Basic Decorating Instructions to tint frosting with white coloring and prepare a frosting bag with size “5” decorating tip. Outline stars with white frosting and pipe to fill with white. Let set about 15 minutes before stacking stars. Top with gumdrop. (Tip: If necessary, pipe a dot or two of frosting between stars to help adhere to each other.)