Several days in advance: Use royal icing to make 6 snowflake arms and center ball. Copy Snowflake Arms pattern and tape onto cake boards; cover with waxed paper. Using royal icing and tip 8, outline 1 snowflake arm at a time; immediately sprinkle on Sparkling Sugar. Excess sugar can be collected and reused. Repeat until you have completed 6 arms (make extras to allow for breakage). Use tip 1A to pipe a 1 1/2 in. diameter ball; immediately sprinkle on Sparkling Sugar. Let all pieces dry 1 to 2 days. Carefully remove arms from waxed paper by sliding a small spatula underneath.
Bake and cool cake. Position on cut-to-fit cake board; place on cooling grid set over drip pan. Cover with Ganache Glaze; reserve any leftover glaze. Let set then position on plate or foil-covered board.
Whip remaining glaze that has thickened to use as icing; pipe tip 8 ball bottom border. Position snowflake arms directly on cake top. Position ball in center.