I know that, at least here in the US, they sell prune puree as an oil substitute for baking. It's supposed to work the same way as applesauce, plus it adds fiber, which is good if you're trying to go for healthy.
I don't know if they sell the same thing there, but it occurs to me that, if you can find strained prunes in the baby food aisle, those might work. It'd be worth playing around with, anyhow.