My soon-to-be 12 year old sister-in-law requested a unicorn cake for her birthday so I had her mom print a line drawing of a unicorn I found online. I drew a 1/2″ outline of the unicorn to enlarge the cake and then cut out the design and used it to cut out the shape of the cake.
I froze the cake then crumb coated it the next morning. I made marshmallow fondant using 2 lbs powdered sugar, 1/2 cup shortening and 16 oz marshmallows. I folded colors into the fondant and rolled out pieces for the mane and tail then used brown to add hooves and facial details (I was out of black). I dusted the cake using a damp paper towel to remove the loose sugar and cooled it before the party.