Remove 1/4 c frosting to a different container. Stir in green food coloring to the smaller container of frosting and orange food coloring to the larger container of frosting until color is evenly distributed and frosting is desired color. Frost “stems” with green frosting and sprinkle with green sprinles if desired. Frost the rest of the cookie with orange frosting. Use candy corns to make jack-o-lantern face: one candy corn each for eyes and nose and 2-3 candy corns for mouth.