Recently, a couple housemates were celebrating a birthday, a considerable success at work/school, and embarking on a journey abroad, all within the same week. While three separate cakes sounded tasty, it seemed only fair that such a big celebration deserved a really, really big cake.
I used a 16" cake pan (available in craft stores), two boxes of cake mix, in which I substituted buttermilk for the water and reduced the oil a bit, to make sure the cake would be solid enough to come out of the pan in one piece. It took three tubs of standard frosting to frost the top, sides, and pipe the wording and border. Next time, I will probably try to make two shallower ones to make a layer cake, because this ended up being quite a thick piece of cake with no frosting in between, but all in all there were really no complaints.
And in case you were wondering, it took them less than a week to eat it. I love my housemates.