I only really had one evening to plan and create Mona's surprise cake, so I settled on a turtle because turtles are cute, Mona loves them, and turtles are sort of flat and round like a cake already anyway. Turtle cake!
Mona's only request was that it be chocolate. Easy enough. Ian was kind enough to bake me a couple of round chocolate layers while I was at work so they'd be cool enough to assemble when I got home. I built myself a turtle shape, put on a crumb coat, and let it all sit in the freezer while I mixed up a batch of fondant.
Fondant is weird stuff. The recipe we use for it tastes pretty good, and in some ways it's easy to work with, but you either get it right or you don't. There's no fixing it or fussing with it later. You either rolled it out well or you didn't, and you get one shot at getting it on the cake. For the most part it worked this time. I got it a nice turtle color, rolled it flat, and draped it onto the clean coat of frosting. (It really helps to get that crumb coat on and chilled when the cake has been cut up first and is extra crumbly. And then I use a knife dipped in water for the smooth coat on top of that.)