I took a look at the Sugar-free Whole Wheat Carrot Cake but it's got Splenda in it which is an artificial sweetener--honestly, I'd rather use something like organic sucanat or whole sugar rather than something that is basically a chemical concoction and is somehow "sugarfree." As long as your child doesn't have a literal sugar allergy, one day of a bit of well-selected sugar shouldn't hurt. You can also take things like apple sauce and reduce it by boiling it and use that as a sweeter--or any pureed fruit as well. Another option is to use stevia which is an herb and 120 times sweeter than sugar--I use it a lot when baking for my son. Or honey--as long as your child is 12 months+ is should be okay. If you want info about where to get stevia in HK, PM me--I just found a good place to find it--affordable too.
Elmo cake, southside852? We're also doing an Elmo cake that will be completely healthy (we're doing individual cupcakes). If you'd like more details about our plan, PM me.