I made a monkey cake in January for this little boy's older brother. We decided to do the same thing for this cake which was one layer of white almond cake, one layer of chocolate cake and french buttercream. The birthday boy's favorite color is red, so I decorated the cake with red. I used fondant to replicate Caillou. I was pretty happy with the results.
I have learned over the years of making cakes that if you want to do two different flavors of cake, you will most likely end up cutting a majority of people two pieces of cake instead of just one because everyone wants to taste both. Then, a lot of cake is wasted because not everyone can finish both pieces of cake. Instead of doing cakes half white and half chocolate, for instance, I prefer to do the two different flavors layered on top of one another. That way, everyone gets a small piece of both in their one single slice. This makes for less waste.