Adapted from a recipe by Marian Burros. This may seem plain, but the combination of tender vanilla cake and fresh, ripe fruit is unbeatable. The recipe originally called for the dark Italian prune plums, but I sometimes use 2 large or 3 medium fresh peaches, peeled, pitted and sliced. I can't decide if I prefer the plums or the peaches! If you can get really fresh fruit from a farm market or orchard, this will be the best dessert you've ever had.