Cake? Seriously? The closest I've ever come to cake (so therefore my best one) was when I got fed to the teeth with rolling out a million little chocolate chip cookie. I mushed all the dough together and made a cake out of it in the cookie sheet, baked a couple minutes longer on a lower temp and had bars, rather than cake, I guess. But they were sure good.
And I found out that when you cut the bars large, it's sounds better when you say you had one bar of chocolate chip cake than 6 cookies.