A cake is done when it is fully cooked. A simple way to test
this is to take a toothpick and stick it in the cake. When you pull
it out, a "done" cake should come out clean and with ease. If you
pull out the toothpick and it sticks a little or still has batter
on it, then the cake is not done.
Make sure you do the "toothpick-test" in the center or deepest
part of the cake. If you think the cake is done, try a few places
ot make sure it has cooked all the way through, too.