One thing I've learned is to make it in the biggest springform pan I have, which means the batter is spread thinly and the plum juices seep out and soak everything.
If you try it, know that as you are assembling it, you're going to think, this is not nearly enough batter. It really gets spread thinly — under an inch — but it's an eggy dough that puffs up a lot as it bakes. Press the plums in firmly, skin side up, so that they're touching the bottom of the pan.
