It's really the best of both worlds. The Plum Crumble at Four & Twenty Blackbirds features pie with a traditional crust on the bottom and a crumble crust on the top. They meet at the rim of the pie, where fresh plum filling, sweet and hearty, oozes over just slightly. That is the single best bite of this crumble. Oatmeal and brown sugar form the base of the crumb topping, slightly spiced and aggressively buttered with a delicate crunch.The plums themselves are tender to the bite, and would make a killer ice cream topping on their own. And say "yes" to their offer of a free side of cream; it's freshly whipped and plopped softly, without a touch of sugar, an ideal accompaniment to any pie.