Prepare and roll out cookie dough 1/8 in. thick. Cut out four moons using cutter from set. Cut off approx. 3/4 in. from the bottom. Turn cutter around and cut out four more moons. Cut off approx. 3/4 in. from the bottom. Bake and cool completely.
To create cake board, place pan upside down and cookies near the mouth area on board and trace. Cut out and wrap in foil.
Prepare buttercream icing. Tint portions black, violet, green and red; leave some white.
Ice inside of mouth and nose area of cake smooth with spatula and black icing. For new mouth area, fill in eye cavities with tip 8 and black icing. Outline mouth with tip 8 and black icing. Use spatula to fill in.
Ice rest of cake smooth with spatula and purple icing.
Pipe teeth with tip 8 and white icing; pat smooth with finger dipped in cornstarch.
Tint coconut black; fill in nose and mouth cavities.
For eyes, insert three gumballs into mouth cavity. Pipe pupils with tip 8 and black icing.
For tongue, outline and fill in with tip 12 and red icing. Smooth with spatula.
Pipe icing between cookies with tip 18 and green icing; sandwich together four similarly shaped cookies for one horn. Position horns next to cake. Pipe lines to cover horns with tip 18 and green icing.