Use any colour combination that strikes your fancy. Scraps are great for this project.

ERRATA!
Row 5 (ruffles), top of cake: ch 2, in back loop only, sl st in 1st sc, {ch 2, sl st in next st in back loop only} 4 times. Leave a long tail for sewing, fasten off.

(changed from “in front loop” only to “in back loop only” - i just noticed while looking at everyone’s finished cake slice! - so sorry >_<)