Okay so the first cake blew up, the second peaked like a volcano, was black on top but still liquid in the middle, the third cake was all black on the outside but also liquid in the middle, the last one was a brownie because unlike cake, I know how to make those. But was apparently "too sweet"
You hollow out the middle, put in w/e then put icing over the whole top. If you do it carefully enough, you can even have the fuse acting as a birthday candle ^_^
So cake first THEN put the explosions in? But how would they fit without looking strange?
... Theoretically.