I altered a cake from "Sweet and Sugar Free"- if you read the reviews at amazon, they're pretty much all true.
- but I added about a T of sugar and experimented with the amount of stevia in dd's chocolate cake for her 2nd birthday, and it came out AMAZING!
I didn't use a "healthy" frosting, so that might have helped, but if I had had more time, I would have figured something out. Dh's birthday cake had whipped ganache frosting, and the result was a rich chocolate thick frosting with very little sugar.