We eat fruit in the summer by the handfuls -- sometimes out of our fridge, sometimes from farmers market stands (yes, we know we're only supposed to try one piece and no, that doesn't stop us). We churn them into ice cream, turn them into refreshing popsicles, and bake them endlessly into bubbling pies and crumbles. But there's one, less-practiced way to put all that delicious fruit to good use, and that's to put them in cakes. Nectarines, plums, peaches, and their warm-weather fruit friends are perfect cake fillers. They keep the batter particularly moist and offer a lighter twist on traditional cakes.