This Motocross Birthday Cake was made from box cake mixes, using the pudding/fudge in them to make them heavier. The bottom layer is two fudge sheet cakes, with mud pie in the middle. I froze the cakes then hollowed out the middle and put in Pudding (that had sat in the fridge for a whole day), gummy worms, and chocolate Oreos. On the outside edges (I only hollowed out the middle leaving a 2 inch border of cake all around) I used the fudge frosting to make them stick. I covered the whole thing with fudge frosting.
The next layer is a 9×13 that I rough cut (after freezing) to make it look like the hill was starting. I placed it about 3-4 inches from the edge of the other cake and covered it in fudge frosting. I then refrigerated the cake. The next two layers are eight inch round white cakes. I used a cake plate for these. The first one is whole, and the one on top is missing about a third of it roughed cut to give the appearance of a hill. Again the whole thing is covered in fudge frosting.
For decorating the boulders are chocolate donut holes, the dirt is chocolate Oreos and chocolate sprinkles, the logs and finish line posts are cookie rods or straws, the grass is green licorice cut, the small rocks are peanut butter cereal, and the flag is fruit rollup. I just kept adding the above until it looked right.