Grease and flour one 9x1-1/2-inch round baking pan and one 9x9x2-inch square baking pan. Prepare cake mix according to package directions adding green or orange food coloring to batter, if desired. Bake according to package directions. Remove from pans and cool completely on wire racks. Trim tops of cakes as necessary to make even thickness.
Cut a 5-inch circle, 3-1/2-inch circle, 2-1/2-inch circle, 2-inch circle from the square cake layer. Stuff some of the cake scraps into the ice cream cone to fill.
Place a small amount of frosting in the middle of a cake plate. Place the 9-inch round cake layer on frosting and press gently to secure (this helps hold cake in place while frosting).
Place about 1/3 cup of the frosting in the center of cake layer and spread to a 5-inch circle. Place the 5-inch round of cake on top. Spread about 1/4 cup frosting in the center of this cake layer and top with the 3-1/2-inch round of cake. Spread more frosting and add the 2-1/2- and 2-inch cake rounds. Insert an 8-inch wooden skewer down through cake layers for added support. Attach the ice cream cone on top with additional frosting.
Frost cake and ice cream cone with remaining frosting (see tip). Decorate as desired with Halloween candies and/or gumdrop moons and stars. Makes 1 cake (12 servings).
Gumdrop Moons and Stars:
Use a rolling pin to roll out gumdrops on sugar-coated waxed paper. Cut out moon and star shapes with hors d-oeurvre cutters. Dip cutters in sugar to prevent sticking.
To spread frosting more easily onto sides of cake: Fill a small resealable plastic bag with about 1 cup frosting. Snip off one corner and pipe frosting onto cake sides. Spread evenly.