Prune-Plum Custard Challah Bread Pudding

This warm, fragrant pudding began as a way to use up leftover holiday bread, but it is so good that I now buy an extra loaf just to make sure I have enough to prepare it for our break-the-fast. Slightly stale challah is fine; if your bread is crispish throughout, you can skip the toasting.

There is a secret here; the flavor derives not only from fresh, blue-black prune plums pumped up with their winy, dried prune cousins, but from the prune pits as well. Stone fruits—cherries, peach