Stack the cakes on top of each other, spreading some buttercream between each layer.
Carve the cake into an owl shape. Cover the entire surface of the cake in a thin layer of buttercream, catching the crumbs in the buttercream. Place the cake in the fridge for 30 minutes, or until the buttercream is firm. Then coat the cake in a generous layer of buttercream.
Place small dollops of black and white candy melts onto a baking sheet lined with parchment paper. Use a clean paintbrush or a knife to smudge the dollops and create brushstrokes. Create a small black feather and a variety of sizes of white feathers.
Transfer the entire baking sheet to the freezer until the candy melts have fully hardened, about 20 minutes.
Stick the brushstrokes to the cake to create Hedwig’s wings, tail and chest feathers. If necessary, use extra buttercream as a glue to attach the brushstrokes.
Dye some buttercream black and yellow, place in piping bags fitted with small, round piping tips and draw the eyes and beak. Enjoy!