I made this cake for my daughter's second birthday, to go along with a trip to the Rainforest Cafe.
To make this cake I started with a boxed mix baked in a tube cake pan. I took two spoonfuls out and placed in a muffin tin and baked that alongside the cake. After removing the cake from the cake pan, I placed a medicine cup in the hole, then the muffin on top, so that the hole in the cake was filled. I then frosted the cake with canned vanilla frosting.
To make the palm tree tops, I tinted ready-made marzipan in a zipper seal sandwich bag, rolled it out to about 1/8 inch, then cut it with a flower shaped cookie cutter. I then folded the petals of the flower so that they were long and narrow, and used a dough roller, rolling outward, to make them a uniform thickness. I placed plastic wrap on the inside of custard cups to make a shallow well, and placed the tree tops in those to dry for a couple of days. I used less than half of a roll of the marzipan, so don't tint the whole thing.
The tree trunks are snack-size Twix candy bars, secured with toothpick halves. I used 1-1/2 bar to achieve the height of the trees surrounding the cake. I used Runts candy for the bananas, and the chimps are plastic figures I found at Target. I stiffened the leftover canned icing by adding powdered sugar, and used this as "glue" to help secure the tree trunk pieces, along with a half toothpick, and also the tree tops.
I made this in the middle of summer, and it was warm and humid, so the tree tops had begun to droop when I served it six hours later, and the chocolate on the candy bars melted in my hands as I was working with them. I would suggest placing the bars and the marzipan in the refrigerator for 30 minutes before assembling, and keep cake refrigerated until serving if the room is warm.
This was my first experience with marzipan, in a last-ditch effort to make the tree tops (I tried finding green fruit leathers(Roll-Ups), making candies, and cookies, but none did the job). I think if I had more time I would have made the monkeys out of marzipan as well, offering more flexibility of posing.