Make candy trees. Tape printable Candy Tree Template to cake board. Tape waxed paper over pattern.
Melt Bright White Candy Melts candy according to package instructions; transfer to decorating bag. Cut 3/8 in. off tip of bag.
Following template, pipe candy triangles, using toothpick to direct candy to edge if needed. Repeat for a total of 76 to 80 triangles.
Chill until set, about 5 minutes.
Bake cake. Prepare cake batter following recipe instructions. Bake and cool 3 cake layers. Level, fill and stack for 6 in. high cake.
Ice top of cake with white buttercream. Lightly crumb coat sides of cake.
Tint icing. Tint 1 cup icing each blue, light pink and dark pink using color combinations provided. Combine Sky Blue and a touch of Kelly Green icing colors to get blue color shown. Combine Pink and a touch of Violet icing colors to get light pink color shown. Combine Rose and Burgundy icing colors to get dark pink color shown.
Using Buttercup icing color, tint 1 cup icing yellow. Using Teal icing color, tint 1 cup icing teal.
Reserve remaining icing white.
Fill 5 decorating bags, separately, with teal, dark pink, blue, yellow and light pink buttercream. Cut 1/2 in. off tip of bag.
Ice cake. Using square comb, lightly comb over sides of cake, just enough to make light indents. Using prepared decorating bags, pipe over protruding lines (leaving indented lines un-iced for now), alternating colors as desired. Use comb to clean up and re-define icing areas, as needed.
Chill until set, about 15 minutes.
Using prepared decorating bags, fill in indented lines. Using icing smoother, smooth sides of cake until lines are uniform.
Reserve remaining tinted icing.
- Pipe swirls. Prepare decorating bag with tip 1M and reserved white buttercream. Pipe swirls around top edge of cake.
Decorate cake. Starting at bottom, use small amount of reserved white buttercream to attach trees to sides of cake. Continue towards top of cake, alternating rows.
Prepare 5 decorating bags with tip 1; fill separately with remaining teal, dark pink, blue, yellow and light pink icing.
Pipe branches on each tree, alternating colors as desired.
Alternatively, branches can be piped ahead of time on the candy triangles. Let the buttercream dry at least 1 hour before placing on cake, taking extra care not to smudge the buttercream.