Aaaaand here's my submission
My entry is a glorious union of cake, sugar cookies, and fluffy marshmallow cream: all homemade of course. =) To give an adequate description of what the cake actually is, a few intermediate pictures are given. I'll withhold the theme until the end of my post, but hopefully it shouldn't be beyond imagination.
As you might be able to tell, it's a bundt pan marble cake. I mixed up a vanilla batter and strawberry batter for the base of the conglomeration. The shape was made by slicing two clockwise spirals opposite each other.

This second picture features the whipped marshmallow cream spread along the outer surface of the cake. Two things of note here: 1) I ended up slicing off the top crust of the cake to show off the marbling. 2) The marshmallow cream was also spread in between layers, but it wasn't very visible :[

The final product. The sugar cookies were made to be a bit tough so they'd stay put after placement and the cookie decorations were done by edible decorative gel (red, white, and black). This actually took a fair few tries to get some decent drawings with the gel, but I think they turned out pretty nicely. The center cookie features a female character dual wielding. Following are a few close-ups of the four peripheral cookies (Mimic, Giant red spider, Red skeleton, Small golem):

If you hadn't figured it out by now, the theme of my cake was windmill =). Although it may not be obvious, the girl in the middle is supposed to be slicing the cake (white cream spirals for effect), and the four other cookies are supposed to be monsters either getting hit or knocked back by windmill.
P.S. If I could have sent in this cake instead of pictures, I totally would have. I can't imagine a cake being tastier than a strawberry/vanilla marble cake with cream filling and sugar cookie topping. Add milk and you're golden.
It's a piece of cake to bake a pretty cake, but making flour is annoying as hell.