I recently did a first birthday Monkey cake for my great niece Isabella also known as Izzy. I basically did a combination of fondant and flavored icing. The letters, number, and monkey are also done in fondant. I did the letters and numbers on toothpicks, an easy way to just pop them right on the cake, but was sure to not make them too thick or heavy.
The cake was a huge success at the birthday party, and she smashed her little one like there was no tomorrow!