To win an icing level, the player must clear all the multilayered icing on the board. Every layer must be cleared, however regular icing doesn't count and doesn't need to be cleared (an empty slot needs to be cleared, though). Extra multilayered icing created by mystery candies needs to be cleared too. In CC071, clearing the last layer of an icing (empty sachet) in an icing level gives you 1,000 points rather than 20, but removing other layers (2nd layer, 3rd layer, etc) will still give you just 20 points.
When all icing has been cleared, a striped candy is made for every move remaining, giving 3,000 points for each. Then each of the striped candies activate themselves.
In CC071, Icing levels are not very common, especially because they are introduced very late (in Level 566) and because even after that level, they are still not common since there are usually 1 to 3 per episode (except in Salty Shores, where they were introduced, in which there are 7 of them). In later episodes, they become even more rare as many episodes don't have any. The song played in this level type is the same as the Timed song on mobile (Candy Order song on Facebook).
In T9CCS, Icing levels are introduced at level 181 in the episode Meringue Mill. They are somewhat common, with the vast majority of episodes containing at least one of them after their release. There are usually 2 icing levels per episode in the earlier episodes, but later their number starts to fall to 1 per episode.
The first icing level is Level 561. Icing levels are not very common, there are usually 1 to 2 levels per episode. In most of their appearances, they are episode openers. Unlike in CC071, each icing layer in an icing level gives you 1,000 points.