Bake the cake mix as directed on the box, in two 8″ round pans.
Allow the cake to cool.
Remove the cake from the pans.
Place one cake layer on a cake plate.
Spread a thin layer of the frosting on the top of the cake.
Place the other round cake on top of the first, being careful to center it in the middle.
Frost the whole cake, keeping the sides smooth.
Sprinkle the top of the cake with ice crystal sprinkles.
Create your Christmas trees, using the candy melt. (See thetutorial. While that recipe makes pretzel Christmas trees, for this recipe we make the trunks out of chocolate melts to make them taller. Using a piping bag, drizzle the green melted candy over the trunks on a baking sheet lined with wax paper. Decorate the trees with mini ball sprinkles.)
Once the trees are cool and hardened, gently press them into the frosting along the sides of the cake.
Store the cake in the refrigerator.
For best results, create your trees ahead of time so you can apply them as soon as you frost your cake.