Once the cake has cooled, carve it as shown. The head and four legs are separate pieces. The body and tail are all one piece. The pieces don't have to be perfectly sculpted. They just define the basic ferret shape. Position your pieces on your serving plate.
Prep one of your decorating bags with the decorating tip. Mix a small amount of white icing into the chocolate icing and stir until you get a marbled look. This will add a little bit of color variation to the ferret's fur.
Place the marbled icing in one of your decorating bags. Squeeze the air out and twist the top of the decorating bag.
Remove the leg pieces and set aside.
Starting at the tip of the tail, begin piping on the icing in the direction of the tail end. You want the "fur" to lay towards the back instead of straight up. Once you cover an area that will have a leg piece against it, lightly press the leg into place in the icing and cover with icing as you did the tail and body, this time pulling the "fur" down towards the plate.
Ice the seam between the body and the head. Press the head lightly in place. Continue with the chocolate icing all over the head leaving blank places across the top of the head and around the nose for the white icing to create the ferret's "mask".
Once the chocolate icing is completed, clean your decorating tip (but do not discard your leftover chocolate icing), place it in a new decorating bag and fill the bag with white icing. Fill in the parts of the face that need the white icing. If you are using 2 decorating bags with tips, you can alternate between your icing colors instead of completely finishing one color before starting the next.
Place a small amount of your leftover chocolate icing in a zippered sandwich bag. Squeeze out the air and close the bag. Using your scissors, snip of a tiny piece off one of the bottom corners of the bag. Twist the sandwich bag as you did the decorating bag with all of the icing pressed toward the snipped corner. Using the sandwich bag, pipe two "C's" on the top of the ferret head for ears.
Position the cinnamon candy for the nose and the chocolate chips for the eyes.
Using the edge of a knife, dab a small bit of white icing on the eyes to highlight them.
All done! Enjoy!