In advance, make 24 candy swirls. Melt light cocoa Candy Melts candy according to package directions. Using cut parchment bag, fill in mold. Chill until set.
Prepare cake mixes according to package directions. (You can use any remaining cake batter for cupcakes.)
For bottom layer, place Batter Dividing Ring in the first prepared pan. Pour chocolate batter in outer and center sections and yellow batter in the middle section. Fill sections 2/3 full. Remove ring from pan carefully lifting straight up on handles. Rinse and completely dry ring.
For top layer repeat step 3 in second prepared pan. Remove ring from pan by carefully lifting straight up on handles. Rinse and completely dry ring.
For middle layer, place clean and dry ring in third prepared pan. Pour yellow batter in outer and center sections and chocolate batter in middle section. Fill sections 2/3 full. Remove ring from pan by carefully lifting straight up on handles. DO NOT PUT RING IN OVEN.
Bake and cool cake according to package directions. Prepare icing. Stack and position cake on foil-wrapped circle
. Ice cake smooth with icing and spatula. Comb sides of cake with decorating comb.
Using tip 18 and icing, pipe seven rosettes on top center of cake as a base for candy swirls; position one swirl on each rosette. Position remainder of swirls around top edge of cake.
Using tip 20 and icing, pipe rosette bottom border.
The rosette has the tight, swirling look of a rose, but is achieved in one continuous rotation, rather than with wrapped layers of petals. Single rosettes are also used as candleholders on top of a cupcake.