This was a lot of fun to make! And surprisingly simple. The cake was made much larger than needed, but only because it's much more life-like at 12" round.
Chocolate cake with chocolate fudge filling, covered in buttercream and fondant. Rice krispies treats covered with fondant make up the "crust." The "sauce" is strawberry preserves mixed with buttercream and a bit of red and brown coloring gel. Everything else on the pizza...ahem, cake...is made from fondant.